Condition monitoring is intended to extend the life time and up time of equipment, including machines, by continuously monitoring their condition, such as vibration and temperature, and using the data to see as a machine is moving away from its normal state (baseline data) and showing signs/signals of a developing fault. This process of monitoring is a major component of predictive maintenance. Parameters that are currently used to monitor the condition of machinery  includes: temperature, vibration and current/voltage through a model based voltage and current systems (MVBI systems). 

The sensors for temperature and vibration tracking have been available for decades, but at ZP we see a that the sensors for monitoring the chemical state of the machine system are not so readily available or are not developed.

At Zimmer and Peacock we are interested in sensors that can measure the chemical condition of a machine, including parameters such as corrosion and the condition of the lubricants.

At ZP we are interested in exploring with clients condition monitoring using our standard sensors including our conductivity sensors for lubricant and fuel condition monitoring.

On this page we discuss the use of ZP Glucose Sensors with the PalmSens Sensit powered by Analog Devices.

In the video we do a show and tell on what is in the ZP Glucose Sensor Kit.

ZP has the largest range of off-the-shelf solutions for people intending to develop wearable and transdermal biosensors. 

As part of our support of industrial and academic developers we will be hosting another webinar including a live demo of wearable tech; the topic for this latest webinar will be ‘Introduction to Wearable Biosensors and Transdermal Biosensor’.

Please register for the webinar below.

At ZP we are passionate about translating ideas around sensing into products. Our focus is biosensors and sensors and so this presentation focuses on difficulties with getting ideas to the market. This presentation is based on original ideas of Geoffrey Moore in his book 'Crossing the Chasm'.

In this video we discuss how to detect a pharmaceutical drug/API using electrochemical techniques specifically we recommend using a carbon electrode.

Links to pages we use in the video are below.

ZP is accelerating our collaborators to market through a combination of off the shelf biosensor products, electronics combined with customization development and manufacturing services, all focused around our core competency of electrochemical sensing and  biosensing.

Two of the tactics we deploy at ZP is to develop the best sensors we can, but to also apply the best data codes and models to the raw data. To this aim ZP is a leader in the application of machine learning to sensor and biosensor product development.

In the adjacent image we show the Machine Learning Implementation Life Cycle that we apply into our clients product development.

ZP is speaking on Thursday 22 October at the Sensors in Medicine 2020, where we will be talking in the wearables and implantable sensors session.

Click the buttons below to find out more.

At ZP we manufacture our pH solid state pH  within our ISO13485 quality management system, applying our standard operating procedures/work instructions and our acceptance criteria. To characterize our solid state pH sensors manufacturing ZP has carried out a multi-step investigation.

STEP ONE - Manufacturing phase

ZP performed a manufacturing step where we manufactured three batches of 108 pH sensors on three different days.

STEP TWO - Testing phase

Next ZP functionally tested five random sensors from each batch. The solid state pH sensors were tested with pH solutions between pH 2 to pH 10, please see adjacent raw data.   As a side note ZP is unusual in that we have both high-throughput manufacturing capability and high-throughput testing capability, click here. This functional test capability was used in this study.

STEP THREE - Data processing phase

Having gathered the data ZP then used our data processing group to apply a mathematical baseline correction to the data, where we mathematically moved all of the data to a baseline of 0 V at the initial pH 2, please see the adjacent data.

This baseline correction is equivalent to a one point calibration. It should be noted that an even more accurate way of calibrating pH sensors is of course to perform a two point calibration, but it was unnecessary for this study. Click here to see our data group.

STEP FOUR - Data analysis phase

Having processed the data ZP next analysed the data.

ZP has a very sophisticated set of technologies and workflows in-house for the conversion of data into actionable information, click here to find out more.

STEP FIVE -  Reporting results phase

The result of our testing was that across all three batches and having performed a single baseline correction 75 % of all the sensors within the population of 324 pH sensors gave  a measured result that was within 85 % of the actual result, i.e. for a pH of 7, the overwhelming majority of the pH sensors from the three batches would read a value in the range 5.95 to 8.05.

We recently had a an enquiry on how to commercialise a biosensor for antibiotic detection.

We have paraphrased the enquiry below, on this page we give a quick response.

... how can we manufacture electrochemical biosensors for antibiotics detection in water bodies , specially how can we make them low cost

1) what will be the manufacturing process 

2) how much time it will take to manufacture them

3) what resources are required for manufacturing,... like plant building, land or amount of space required and people required for manufacturing processes

4) what can be its estimated shelf life 

5) how can we design it 

ARTICLE FROM DIACEUTICS

For those who are looking for a higher resolution on  the activities and the costs behind Professor Heller's comments then we find an article from Diaceutics is excellent. The original article is here - click here.

In the adjacent table we have read and understood the information from Diaceutics and added our own take on their numbers.

You can see that Diaceutics gave a value in the range $20 M to $100 M which is inline with Professor Heller's comments.

CONCLUSION

At ZP we are always excited to work with clients who are ambitious and are driving to the market, and of course we want to support people on this road. We hope that these notes will help people in their buisness planning and their buisness models.

If you have questions regarding ZP's contract development and manufacturing services for IVD, please don't hesitate to contact us.  

Zimmer and Peacock has the worlds widest range of electrochemical sensors and biosensors on the market. Our customers, clients and collaborators  can engage with our technology, either by:

1) Partnering with us through one of our off the shelf solutions.

2) Contracting with us to develop and manufacture a bespoke sensor.

Below we link to the sensors and electronics appropriate to developers of water quality monitoring applications.

The sensors in the ZP biosensor range applicable in water quality applications include: conductivity/salinity, sodium, potassium, phosphate, ammonium, calcium, pH, chloride and oxygen.  If you can't see the sensor you are looking for please don't hesitate to contact us.

The ZP Group is under going massive growth, but we know that the foundation of growth is having  excellent clients and an excellent team, where our team is  delivering world leading services and products to our clients.  

For the ZP Group growth to be sustainable we fully appreciate that we have to increase our team and our network and so we are reaching out through  our primary, secondary and tertiary connections for individuals who can participate in leading our spin out ventures. 

We have a number of internal and external programs within the ZP group that are maturing and will require substantial funding, but ZP understands that funding needs to be linked to an effective CEO; that is why ZP is reaching out through our network for people with the intelligence, drive and organisational skills to be part of seeding and running new ventures.

The ZP Group is focused on electrochemical biosensors and the real world applications of these sensors, so please assume that you would be coming into a rich ecosystem of engineering and scientists centered around the deployment of sensor and the delivery of sensing data into business and/or consumer actionable information.

At ZP we know that  the conversion of world  beating capability into market ready products and services will take great leadership, energy and focus from individual who can share a vision.

If you want to start exploring the next step in your life, with a view to seeding and running a business, please don’t hesitate to contact Even or Martin through linked in.

Please click click below to contact Even on LinkedIn

The ZP Group is looking to grow our geographical network and reach in part through our ZP Cell Network.

Our ZP Cell Network is looking for talented scientists and engineers, with a background and/or an interest in electrochemical biosensors who want to collaborate with the ZP Group.

ZP has a global customer base and so we are looking for truly entrepreneurial scientists or engineers geographically distributed, who can engage with our ZP team and support our clients and programs in their region. 

If you are interested to be part of our ZP Cell Network, please contact us.

Welcome to ZP's resource page for developer of biosensors who are looking to develop a biosensor on a gold electrode, using self assembled monolayers. 

The principles that summarize the content of this page includes, the electrochemical detection of biologically relevant molecules through the specific binding of an analytes to a surface, where the detection technique is electrochemical. The techniques we promote include: electrochemical  impedance spectroscope (EIS), differential pulse voltammetry (DPV), square wave voltammetry (SWV), chronoamperometry (CA), etc.

How to form a SAM layer.

Recommended potentiostats.

Obtaining a signal.

Contact us.

ZP had a series of questions regarding our sensors, which are listed below so we decided to answer them in a video, see the questions here.

 glucose,

1. Resolution:

2. limit of detection:5mM

3. redox potentials:

4. Interval concentration: 0-20mM

5. etc

 lactate, 

1. Resolution:

2. limit of detection: 1 mM

3. redox potentials:

4. Interval concentration: 0-4 mM

5. etc

sodium and 

1. Resolution:

2. limit of detection: 40 mM

3. redox potentials:

4. Interval concentration: 0 - 360 mM

5. Sensitivity:  0.02 Log (C)/mV

6. etc:

potassium

1. Resolution:

2. limit of detection: 2.7 mM

3. redox potentials:

4. Interval concentration: 0-7 mM

5. etc

At  ZP and Aliksir we are manufacturing our first batch of electrochemical biosensors for the direct detection of SARS-CoV-2 as our contribution towards the fight against COVID-19.

Our rapid development of this sensor was made possible because ZP's  team has now been together for over six years and delivered on over fourty biosensor development  and manufacturing programmes. The ZP team spans from biology through electrochemistry and electromechanical  to quality engineering.

For this sensor to truly be impactful we are looking for companies and entrepreneurs who have the vision and resources to take this all the way  to market with us.

Please don't hesitate to contact us if you have a vision to get this thing beat.

Welcome to our discussion on the electrochemical detection of COVID-19 using reverse transcription polymerase chain reaction (PCR).

Though PCR is entering the widely used lexicon it is not always understood; a simple definition of PCR is a method by which DNA can be amplified so that it can subsequently detected or measured. The term amplification in this context means that the amount of DNA is increased (multiplied) by the polymerase chain reaction.

There is a hyphenated version of PCR, which is relevant when discussing COVID-19, this is real time PCR, also known as quantitative PCR (qPCR). In qPCR it is possible to measure the amount DNA as a function of time/cycles.  The time it takes for DNA to be detected is proportional to the amount of target DNA in the original sample and so the real-time PCR/qPCR can be a quantitative. 

Of course, COVID-19 a virus and hence has RNA as opposed to DNA. Therefore, when you look at the tests on the market for the detection of an active COVID-19 infection many are best described as RT-PCR, where the RT stands for reverse transcriptase. The sequence of events in aCOVID-19 RT-PCR is that the COVID-19 RNA first undergoes transcription from RNA to DNA, and subsequently the DNA is amplified (multiplied) and in real time the amplification of the DNA is measured.

A flaw in RT-PCR detection of COVID-19 is that it often involves a fluorescent t dye, and it is the binding of this dye to the amplified DNA from the PCR, which is the source of the signal. The issue is that it is hard to make fluorescent base instruments low cost and portable. When you look at the list of commercial fluorescent-based RT-PCR instruments for COVID-19 the smallest are tabletop units, and none can be described as handheld and low cost.

What is required is a small handheld COVID-19 RT-PCR instrument with the same costs and size as a glucose meter.  In order to achieve this the detection science has to be transferred from fluorescence to electrochemistry. All handheld glucose meters on the market are based on the science of bio-electrochemistry, which allows them to be manufactured at relatively low prices.

To convert a fluorescence RT-PCR to an electrochemical RT-PCR is straightforward with a lot of examples in the literature, and a simple google search on ‘electrochemical RT-PCR’ will yield pages of academic hits.

At ZP we have a number of technologies available through our webstore to help those wishing to develop low cost RT-PCR COVID-19 tests using electrochemistry, please don’t hesitate to contact us.

THE SENSOR

The classic way to functionalise an electrode towards a virus of interest is to immobilize an appropriate macro-molecule to the surface of an electrode. The function of the macro-molecules to give the electrode specificity towards COVID-19.

The technology commonly used to immobilize macro-molecules to electrodes is SAM (self-assembled mono-layer).

In the adjacent buttons we provide some information on anyone thinking of developing a COVID-19 biosensors using gold electrodes and SAM technology.

THE ASSAY

Zimmer and Peacock's philosophy for COVID-19 assay development is try and keep it simple. Therefore in the adjacent button we discuss a philosophy on how to design a viral assay, whilst keeping it simple.

THE ELECTRONICS

Zimmer and Peacock has a wide range of electronics for COVID-19 biosensor developers, from their R and D phase through to their product launch.

We have included some useful buttons here, but we would highlight the FoodSense platform, as this platform has a readiness level that is useful within the timescale of the current COVID-19 crisis.

CONTRACT DEVELOPMENT AND MANUFACTURING SERVICES

Zimmer and Peacock is a dynamic team of IVD developers and manufacturers, if you want to discuss your development and manufacturing needs for a COVID-19 assay please don't hesitate to contact us.

At Zimmer and Peacock we are experts in developing and manufacturing electrochemical biosensors. One of the  strength of the company is our broad understanding of applications including the analysis of wines.

Many of the aromatic molecules within wine including the polyphenols, tannins, anthocyanins, flavonoids are detectable by our technology. At the same time our sulfite in wine  and pH sensing technology can augment the characterization of wine.

ZP can implement our core technology either for discrete single point testing or in a continuous analysis mode where the wine is monitored as a function of time.

We have put some buttons below to help people explore our wine centric expertise and technologies, including  a link to our AI technology. We see wine and  AI being a powerful combination  due to the complex chemical matrix of wine.

Selectivity of ISE

When answering the question 'what is the selectivity of an ISE?' it is useful to use the selectivity coefficient.

The higher the selectivity coefficient value of, k, the more selective the ISE is towards X relative to A.

Sodium ISE

If we use the example of the ZP sodium ISE, then we have the following selectivity coefficients:

• k Na,K 0.6
• k Na,NH4+ 0.2
• k Na,Ca2+ 0.02
• k Na,Mg2+ 0.03

These selectivities   can be interpreted by understanding the ratios of these ions within the application, e.g. if the Na/K ratio is > 20 then there is no significant interference of potassium ions with the ZP sodium sensor.

Similarly if the Na/NH4+ ratio >10, then again there is no significant interference from ammonium and finally if the Na/Mg or Ca ratio is >1 then there is no significant interference of these ions to the ZP sodium sensor.

Whether the ZP sodium ISE is specific enough relative to ions such as potassium  depends on the application of interest. If we consider sea water or blood then the sodium to potassium ratio is intrinsically high.  In the case of blood the sodium concentration is approximate 135 mM whilst the potassium concentration is approximately 4 mM , therefore the Na/K ratio  = 34, so the ZP sodium ISE sensors is not effected by potassium within this application.

Potassium ISE

The ZP potassium ISE uses a very selective ionophore, and so the selectivity coefficient of the ZP potassium sensors means an excellent selectivity towards potassium in the prescence of other ions, as reflected in the selectivity coefficients:

• k K,Na 0.0004
• k K,NH4+ 0.01
• k K,Ca2+ 0.003
• k K,Mg2+ 0.0001

In this video we show you how to run a first experiment for ferri/ferrocyanide on a ZP potentiostat and screen printed electrode.

All the equipment used in the video can be found here.

Applications are invited for a three-year MPhil/PhD studentship. The studentship will start on 1 st October 2020.

Project Description

Fundamental understanding of protein dynamics, energy landscape and conformational changes, is central to deeper insights into a protein’s specific biochemical functions (such as allosteric signalling, enzyme catalysis etc.). This could aid in drug discovery, novel protein engineering and distinguishing between normal and pathogenic conformational changes for disease diagnostics applications. In this project we aim to investigate a novel approach for the detection of protein dynamics and interactions on the surface of Graphene (and related two-dimensional materials, G2DM) through direct comparison of Molecular Dynamics Simulations (MDS) with experimental results obtained from our G2DM based sensors developed at the University of Plymouth in collaboration with the University of Cambridge.

For the MDS we will employ the Kohn–Sham (KS) formalism of the density functional theory approach to perform the in-silicio study of the graphene-protein system. The KS approach has proven to be one of the most efficient and reliable first-principles methods for investigating material properties and processes that exhibit quantum mechanical behaviour. The pioneering

nature of this research will enable the student to use BigDFT massively parallel electronic structure code to simulate the graphene-protein sensor, based on the High Performance Computing Cluster at the University of Plymouth, as well as making comparisons with cutting edge experimental measurements. Accurate comparisons between MDS and experimental

results has the potential to lead to a breakthrough in our understanding of protein dynamics and conformational states, thus opening a plethora of applications in diagnostics, prognostics and therapeutics particularly for Alzheimer’s, cancer and cardiovascular diseases. 

At Zimmer and Peacock we have a can do attitude and so during this COVID-19 pandemic we are busy validating biosensor solutions to help protect public health.

We do understand that the best solution is a vaccine but until that is readily available ZP will do it's part and continue to validate the COVID-19 test.

Thank you for attending our talk today at USN, please download the presentation here.

If you are interested in having a collaboration with ZP please contact us.

Recently one of our engineers walked a client through the set up of their ecFLEX - a wearable biosensor platform.

In this note we report the guidance that the engineer gave.

STEP ONE - Connect the ecFLEX to the sensor.

STEP TWO -  Connect the battery to the ecflex using the crocodile clips (the black crocodile clip is isolated underneath to avoid shorting) and keep the black crocodile clip on the side near the components.

STEP THREE- Once the ecFLEX is powered download the readout software.

STEP FOUR - Once the readout software is up and running, you have to press scan and find your ecflex listed (Tx should be higher than -127 dBm).

STEP FIVE - You connect to your device by double clicking the name of your device and waiting for the settings to upload (everything will be automatic, you do not need to change anything in the software settings). Once the device is connected, the Tx will show -127 dBm so do not worry:

Lastly one of our engineers put out a super useful video on YouTube, please watch to lean more.

ZP's hydrogen peroxide sensor for vaporized hydrogen peroxide detection  is a handheld mobile system that can be deployed to measure the hydrogen peroxide vapour in an atmosphere.

ZP's VHP meter can be deployed during decontamination to check  the vapour hydrogen peroxide levels, and post decontamination to ensure that levels are safe for  operators. 

ZP's VHP meter is unique as the world's only handheld portable VMP meter. Further it is the only meter to use enzyme technology to detect hydrogen peroxide so is inherently the most specific hydrogen peroxide meter on the market.

The ZP cartridge system means that the hydrogen peroxide sensor can easily be replaced in the field and avoids  having to send sensors back to the factory for calibration.

At Zimmer and Peacock we appreciate the importance of having a good connection between your microneedle array and your electronics,so that you can have the best possible signal.

So many of the biosensors from Zimmer and Peacock fall  into the category of Ion- Selective Electrodes (ISE), at the time of writing the list includes: pH, potassium, sodium, chloride, calcium, nitrate, ammonium and phosphate.

Some of the these ISE sensors can be seen in action by clicking  the button below.

At Zimmer and Peacock we have a lot of characterization data, some of which is on our website, but if you can't find what you are looking for please contact us.

One of the technical advantages of the ZP ISE is that they can come with a chloride resilient electrode, so that the sensors can be used in applications where the chloride ei sunnow or uncontrolled.

When people talk about multiple sensor system and the IoT they are describing multiple sensors monitoring a system be it a body of water, a manufacturing process etc.

Traditional chemical sensors, such as the glass barrel pH sensor, do not translate well into multiple  sensor networks. This is because traditional sensors were originally designed for lab applications, where low cost and robustness were not considerations alongside functionality and accuracy.

At ZP we know that when you combine electrochemical sensing technology with low cost manufacturing principles you are able to manufacture a sensor with the right cost and functionality. 

At ZP we have an extensive range of sensors, where the fundamental technology and manufacturing principles makes them perfect for those working on sensor network products.

At Zimmer and Peacock we are focused on electrochemistry, both from the research perspective but also from the commercialisation perspective.

Below we have linked to resources on our website regarding electrochemistry be it:

1) Energy Conversion and Storage - Fuel Cells, Bio-fuel cells, Batteries and Flow Batteries, Electro-catalysis and Photo-electrocatalysis.

2) Photo-electrochemistry - Solar Cells, Perovskite, and alternative Solar Cells.

3) Corrosion - Marine Corrosion, Coatings, Paints, Polymers.

Please click the buttons below to access extra resources or contact us to ask specific questions

One of the keywords that describes us at Zimmer and Peacock is electrochemistry and so we approach the development of sensors and sensing from an electrochemist's perspective. That is why when people ask us can we provide or develop a sensors for heavy metal detection the answer is YES, but most importantly we also approach the answer form the perspective than for an electrochemist heavy metal detection is an 'easy' and well understood technology.

In the adjacent image we show the wave form and expected raw data from analysing a solution of heavy metals.

The technique that we recommend is anodic stripping which is an analytical technique that involves preconcentration of a metal onto an electrode surface followed by selective oxidation of each metal during an anodic potential sweep. 

Stripping analysis has the following properties: 

1. Sensitive and reproducible (RSD<5%) method for trace metal ion analysis in aqueous media.
2. Concentration limits of detection for many metals are in the low ppb to high ppt range (S/N=3) and this compares favourably with AAS or ICP analysis.
3. Field deployable instrumentation that is inexpensive, approximately 12-15 metal ions can be analysed for by this method. 

The method is quantitative a the stripping peak currents and peak widths are a function of the metal concentration in solution.

As stated above this note is specifically focused on pH sensors, and the problem that we are trying to solve is drift in pH sensors which are expected to be in continuous use for hours/days.

We have illustrated the problem in the adjacent figure, where a pH sensor is in a constant pH solution at a constant temperature and the signal is stable/perfect. The reality is that the signal can/does drift. In this note we explain the maths behind the senors and where the source of drift could be coming from and then calibration routines to counter the drift.

In the adjacent image we have started with an equation based on the Nernst Equation, Equation 1, and rearranged it to Equation 3. If we look at Equation 2 it says that the raw signal will be constant when pH, temperature, constant 1 constant 2 and constant 3 are all stable. What Equation 3 indicates is that to remove the influence of temperature from the signal either the analysis should be done at a controlled temperature or the sample temperature should be monitored. 

The reality with pH sensors is that constant 1, constant 2 and constant 3 are not stable, and so if you have wondered why there is always/often bottles of pH calibration solutions next to the lab pH meter it is because of the drifts in these constants; in the rest of the note we discuss re-calibration techniques.

ONE POINT CALIBRATION

If it is only the Constant 1 in Equation 3 that is drifting then a one point calibration is sufficient. What we mean by this is that a solution of known pH is placed in contact with the sensor and the Constant can be calculated from Equation 4. The now re-calculated constant can be put back into Equation 3 and the accuracy of the system improves and the drift in the raw signal will not be reflected in the displayed pH.  In the adjacent image we show raw data from a ZP pH sensor, the steps in the data reflect the changes in signal as the pH is changed from pH 2 to 9 and back again. It should be noted that the sigan is stable over 1600 seconds/30 minutes. We would therefore suggest that the ZP sensors are at least stable over 30 minutes and shouldn't require calibration in that time. Please note a one point calibration is most effective when measuring a sample that should be at a specific pH, for example pH 7.2. In this case one uses a calibration solution that is similar to the sample solution and is also buffered at pH 7.2

TWO POINT CALIBRATION

A one point calibration described above is fine if we assume that the drifting is due to the Constant 1 in Equation 2, but is due to the pH Sensitivity drifting  then we need to perform a two point calibration. In the embedded excel file opposite we have embedded the maths to do a two point calibration. To make the spreadsheet work, then the user/system needs to expose the sensor to a calibration solution at pH 4 and record the mV signal (the default in the spreadsheet is 150 mV), next the user/system needs to expose to pH 10 (the default in the spreadsheet is pH -60), from that the spreadsheet calculates the Constant 1 and the pH Sensitivity. These values can be placed back into Equation 4 and the overall system will then calculate the pH more accurately. Typical values used to calibrate a pH sensor are 4 and 10 but the best way to get an accurate calibration is to use calibration solutions whose pH values are reflective of the expected pH range of the solution.

HARDWARE SETUP FOR RECALIBRATION

In the adjacent image we show an example of a hardware setup that can be used for one point and two point calibration.

TEMPERATURE COMPENSATION

The topic we have not yet discussed in this note is temperature compensation, please note that this page is a live page and ZP are busy gathering the temperature characteristics of the pH sensor.

At ZP we are aware that we have 'too many' biosensors, and as the demands of our clients increase and as many approach the market then we have moved to improve the sensors. In this note we discuss that the sodium sensors have been improved in two important ways:

1) CHLORIDE RESILIENT - We now have a sodium sensor that is chloride resilient, what we meant by this is that the reference electrode does not change it's voltage as the chloride concentration changes.  In many blood, plasma and serum applications the chloride concentration is fairly fixed at around 150 mM and so the fact that the silver/silver chloride reference electrode is chloride sensitive doesn't matter, but in other fluids this is not the case. In the new sensor the reference electrode is  chloride resilient and so suitable for applications where chloride is variable or unknown

2) LONGER TERM STABILITY - In the adjacent image ZP has run two of its chloride resilient sodium sensors in 40 mM sodium solution for 64 hours. Both sensors kept within a 40 mV wide band. This would mean that the sensor was showing a change that was equivalent to going from 40mM to approximately 160 mM. Both sensors were on the same solution but were in fact run on separate instruments. This would make one think that something extrinsic to the sensor and the solutions was causing the solutions/sensior to change its apparent sodium concentration; an obvious parameter would be temperature. One would conclude that if we repeated the experiment but with temperature control then the apparent stability would be improved.

As we suspected that our data had been influenced by temperature we repeated the test but in a lab with a much better temperature control. The result was that after the initial setting time the signal was more stable so provides evidence that the sensor is temperature sensitive and so oen will either monitor or control the temperature when in use

Who should come?

Anyone who is interested in developing and commercialising sensors based on electrochemistry.

What will happen?

This will be a highly interactive course/workshop, people will be encouraged to interrupt and ask question as we go along, you will do real practicals in our labs, so it WILL NOT all be theoretical.

Workshop content?

Please click the button below to get a flavour of the course.

Price?

The workshop will be  750 Euros and does not include accomodation.

Accommodation?

Please click the link here to see the hotel in walking distance - link.

At ZP we are super interested in many  types of biosensors including pH sensor. At ZP we appreciate that pH sensors have not changed in 40 years, so at ZP we are leading the revolution in updating and upgrading pH sensors both for discreet and continuous  monitoring.

The technology at ZP offers pH sensors at a few cents per sensors when purchased and used in volume.

In this note we describe the continuous monitoring of the pH levels of the media within a bioreactor, specifically we have used E. coli DH5α which has been  cultured in lysogeny broth (LB) for 24-48 hours. During this time the sensor was

recording the potential/pH of the solution by OCP. The sensor was tested for pH sensitivity using the standard pH4, pH7 and pH10 reference solutions at 10 minute intervals both before and after the microbiological test to firstly ensure that the sensor was pH sensitive before the test began, and secondly to assess what impact (if any) the exposure to the

bacterial solution had upon the sensors pH sensitive properties.

INTRODUCTION

At Zimmer and Peacock we are pragmatists, which means we will choose the best materials for the particular application.  When manufacturing a screen printed electrode the choice of ink can be critical or not depending on what the ink will be used for.  When it comes to sensors and  assays developed on screen printed

In this note we discuss a comparison between two carbon inks from two different suppliers. When choosing an ink there are generally two categories of properties that are that .are considered and one that is overlooked, these are: printability, electrical properties and electrochemical properties.

The printability/rheological properties of an ink and paste are of course in the datasheet of the vendors, and similarly the electrical properties of the ink appear on the datasheets. What is not so much discussed is the electrochemical properties of the ink.  Whether the electrochemical properties are important then depends on what kind of assay is being run, whether is is an impedance, amperometric, voltammetric or potentiometric assay.  There are no definitive rules, but one could argue that electrochemical properties are important when the assay is voltammetric in nature. If the assay is potentiometric for example then the electrochemical properties are less important.  We illustrate this within this article.

See our low cost SPE

Explore our low cost SPE

WAFER MAPPING

Once the inks were printed ZP used its wafer mapping technology to assess electrodes fabricated from A and B.

ELECTROCHEMICAL TESTING

Both inks were tested for their electrochemical behavior, and whilst Ink B gave reasonable peaks, ink A did not give the expected electrochemical behavior.

FUNCTIONAL TESTING

Having determined that the electrodes were electrochemically different we could clearly say that for a voltammetric assay ink B performed better than ink A. We then tested both as amperometric and potentiometric sensors. Following these tests we could argue that both ink A and ink B were able to be used in the amperometric and potentiometric inks.

WHY ARE THE INKS DIFFERENT

In the adjacent image we show the route cause of while both inks are conductive one is better for voltammetric assays; the root cause is the ratio of organic binders to metal/metalloid on the surface. Higher the ratio of organic binder to metal/metalloid then the higher the resistance and therefore the more distorted the voltammetry .

ZP knows that one of the futures for the garment and sportswear industry are wearable biosensors. All the easy parameters such as ECG, pulse, temperature have been measure, BUT at ZP we are tackling the hard parameters, including: lactate, glucose, hydration, pH, sodium, potassium in a wearable format.

Our mission at ZP is to accelerate the time it takes get smart wearable biosensors to market.

ZP is a super friendly company so please don't hesitate to contact us.

OVERVIEW

At Zimmer and Peacock we carry our contract development and manufacturing of electrodes, sensors and biosensors. ZP is different in that we understand and can perform the entire workflow from: printing to functionalizing, to addition of microfluidics to final calibration of batches.

In this article we expand upon this and describe some ways of getting to market quicker.

MANUFACTURING ELECTRODES 

The issue with any custom manufacturing is that great manufacturing accuracy and precision comes with manufacturing volume, and in the same way low cost and high yield also comes with manufacturing volume. What we mean by this is  'the more you make something, the better you are at it'.

If we take the example of custom screen printed electrodes we receive a lot of requests for custom screen printed electrodes, but  when we look at the designs you discover that they are all fairly similar. At ZP we have both standard electrodes and we also provide custom manufacturing services.

The benefit of using a ZP standard product, particular our value electrode range, is that they are already a high volume manufacture piece has gone through the wafer mapping process. The advantage to our customers, clients and collaborators is that they can purchase just two electrodes to try out, or thousands of electrodes which have already been functionally tested.

FUNCTIONALIZING ELECTRODES

Zimmer and Peacock is unusual in that we can both manufacture electrodes but we can also functionalize the  electrodes to make them specific; the materials we are used to handling include: aptamers, ionophores, enzymes, DNA antibodies, antigens etc. Zimmer and Peacock has a number or pre-existing sensors and biosensors which can accelerate the time to get to market.

TESTING

At Zimmer and Peacock we are often asked to do custom/contract manufacturing of screen printed electrodes.  At Zimmer and Peacock we take a more holistic approach to the screen printing of electrodes for sensor and biosensor applications.

Electrodes on the R and D market are often shipped functionally untested, what this means is that the electrodes are visually inspected but appearance is not a god assessment on how an electrode will function as  a biosensor. ZP is different in that we are able to electrochemically functionally test electrodes and sensors before shipping; at ZP we call this process wafer mapping.

MICROFLUIDICS

Self filling/capillary filling is a feature common on glucose electrochemical sensors/strips; at ZP are able to provide this technology either as a custom part or as a standard product; again the use of the standard product reduces tiem and the cost to our collaborators.

ZP will be exhibiting at Lab-on-a-Chip 2019 at San Diego come and see us there.

ZP will be exhibiting at the AACC in Anaheim, please come and see us there at both 1299.

ZP will be exhibiting at Sensors 2019 in San Jose, please come and see us there.

ZP will be exhibiting at MDDI Boston.

Come and meet ZP at the IFT in New Orleans, we will be exhibiting.

Zimmer and Peacock will be attending the ASTA conference in Naples Florida, come and see us there.

ZP is a world leading contract developer of sensors, biosensors and IVDs. In this note we discuss a strategy ZP can use on your programs to accelerate the time it takes to get to to market.. The strategy discussed  works in a number of businesses and technical  scenarios, including where the strategy is to perform a 510 K submission.

The traditional way of developing a sensor, biosensor or IVD is to spend several years developing the sensors and then going into the field and/or clinical setting and starting testing on real samples. This is a sequential effort and means  that too much time is spent tuning the assay on samples that are not representative of the the real world samples. In addition the methods used to extract the signal from the raw data are often highly manual with many teams recycling techniques used in the past. For example glucose signals are often measured by using chronoamperometry and chronocoulometry, but this ignores the plethora of other techniques available to the development team.  Further with the slow traditional strategy it ignore the simple fact that investors give a company a higher valuation if it has data on real samples; therefore at ZP we think it is important to get to real sample data ASAP, and rather than sequentially building the sensor technology and then gathering real world data, the two efforts should be in parallel and/or overlapping.

At ZP we rapidly move you to real world samples, using a three phase approach.  The advantage that the signal extraction algorithm is tuned on real sampes, whilst also gather real world sample data, the phases are::

1) PHASE ONE - ZP develops your proof-of-principle assay on our pre-existing electrodes and our AnaPot electronics; upon completion of a proof-of-principle study we can translate the results onto a some hundreds/thousands of functionalized electrodes and start testing with real samples.

2) PHASE TWO - ZP and you perform some initial test with real samples to ensure that the new diagnostic/sensor is approximately working.

3) PHASE THREE - This is a preclinical study on some hundreds of real samples. This PHASE THREE involves two parts:

• 3A - TRAINING PHASE
• 3B - TESTING PHASE

3A - TRAINING PHASE

As discussed above ZP collects data on hundreds of real world samples using both the new technology and the predicative technology, subsequently we split the data randomly into a training data set and a test data set.

With the training set of data we use the ZP Signal Extraction Loop Training Phase Strategy for developing the calibration/extraction algorithm for your device.The output from the training phase is an algorithm to extract the analyte signal from the raw data.

OPTIMIZING THE SIGNAL EXTRACTION ALGORITHM

As discussed above the technology provided by ZP will over analyse the samples so that we can extensively mine the raw data. The strategy is to develop a signal extraction algorithm which leads to a  minimum error between the new diagnostic and the existing/predictive diagnostic.

The ZP signal extraction algorithm will automatically loop/iterate until the error betwen the existing/predicative device and the new device is minimised, see adjacent figure.

3B - TESTING PHASE

 As discussed above, he data for the testing phase was in fact collected during the training phase, but now the signal extraction algorithm developed in the training phase is used to extract the signal form the test data set, and a Deming regression analysis performed to ensure equivalence between the predicative assay and the new assay.

If you have any questions regarding how ZP can help in the development and manufacturing of your sensor, biosensor IVD, please don't hesitate to contact us.

RAW DATA

In the adjacent image a ZP CGM sensor is tested over a range of glucose concentrations.

In this example of raw data from a CGM we can we how the current increases with glucose concentration.

CONVERTING RAW DATA TO INFORMATION

Our raw data from the image above can be converted into information in the first instance by plotting signal versus concentration; we have illustrated this in the adjacent figure;  we have analysed the signal at each glucose concentration and made a calibration curve with a linear fit.

c0 = base line

c1 = gradient/sensitivity.

SENSOR DRIFT

The question with any sensor that is to be used for continuous monitoring is 'how much does the sensor drift?'

In the adjacent image a sensors was tested over several days and the raw signal is plotted against the glucose solution used to test the CGM.

In this theoretical example the sensors has lost approximately 35 % over the test time; there are two potential solutions in this scenario:

ONE - Reformulate the sensor so it is stable.

TWO - Have a periodic calibration routine with a known concentration in a  calibration solution and adjust the sensors calibration factors.

CONVERTING RAW SIGNAL TO INFORMATION

In the sensor drift data above for a theoretical CGM sensor there are two parameters, that  can drift with time, the baseline and the sensitivity, the volume of raw data can be reduced to two parameters which can quantify the overall sensors drift by calculating the baseline drift and sensitivity drift.

Zimmer and Peacock are  world leading contract developer and manufacturer of sensor, biosensors with a wide range of application experience including continuous glucose monitoring (CGM), if you have any questions please don't hesitate to contact us.

It can take millions of dollars of money and effort to lock-down the manufacturing of biosensors and medical diagnostics. Therefore, you must have some out of the box thinking to be able to get your initial biosensor product ready for market and on the shelves. 

At ZP we work to make the biosensors and manufacturing as good as they can be, but we also use supporting technology like RFID tags to carry important data about the sensors into the field. RFID tag technology allows the manufacture test data to be carried with the sensor out into the final application, the result is an overall sensor performance that is superior to just the manufactured sensor product.

At ZP we perform a lot of testing and characterization during the manufacturing process and this data can influence the sensitivity and performance of the final product.

ZP is the only contract biosensors and medical diagnostic company able to send deliver biosensors with individual calibration factors for maximum infield performance.

Zimmer and Peacock has had a record breaking 2018, and so the team is really looking forward to 2019.

Please don't hesitate to contact us with all your biosensors and medical diagnostic development and manufacturing needs.

What's wrong with some of the methods of measuring pH? At ZP we recently discovered the answer to this question whilst working on a novel application, and the answer is that potentiometric measurements using oxide based sensors can take some time to reach equilibrium, When we say 'some time' we specifically mean 200 seconds, which may not sound like a lot, but if you want or need to know the pH of a sample within 30 seconds then 200 seconds is too long.

At ZP we have a different attitude to problems, as we seem them as opportunities and so when faced with a challenge of needing a fast to respond pH sensor, we changed the mode of operation and the chemistry of detection; what we created was a ZP voltammetric pH sensor which was able to measure pH within 30 seconds.

What is not widely appreciated is if you can record a spectrum such as a UV-VIS spectrum then you are almost guaranteed to be able to obtain an equivalent electrochemical voltammetry spectrum. For example if you have a molecule of interest and you can measure the UV-VIS spectrum, then you can record the equivalent electrochemical spectrum, this is shown in the adjacent image.

The existence of an electrochemical spectrum for every optical spectrum, in ZP's experience, is universally true, we show another example in the adjacent image.

ZP is delighted to be exhibiting alongside Zahner at ECEE in glasgow.

The Electrochemical Conference on Energy and the Environment (ECEE 2019): Bioelectrochemistry and Energy Storage will be held in Glasgow, Scotland from July 21-26, 2019 at the Scottish Events Campus (SEC). This international meeting will focus on the following areas:

• Lithium-ion Batteries: From the Design of New Electrode Materials and Electrolytes to the Performance and Recycling of Industrial Systems
• In Situ and Operando Characterization of Energy Storage Systems
• Mass and Charge Transfer Across Electrochemical Interfaces
• From Qualitative Models to Quantitative Predictions
• Alternative Battery Chemistries and High-power Devices
• Metal Anodes Meet Solid Electrolytes
• Enzymatic Bioelectrochemistry
• Microbial Bioelectrochemistry
• Bio-inspired Electrocatalysis

Zimmer and Peacock is located in the USA, Norway and the United Kingdom, but our perspective is global and so this week we were in South Africa delivering our biosensor, sensor and medical diagnostic technologies to partners there.

Zimmer and Peacock have been busy going on site and testing garlic products with our garlic sensors.

ZP is delighted that many of our clients are now using the ZP ChilliPot to test their products as part of the QC in production.

THE PROBLEM

At Zimmer and Peacock we develop electrochemical sensors, biosensors and medical diagnostics;  something that is rarely mentioned both in the academic or industrial setting is the reference electrode. Often the reference electrode is silver/silver chloride, but the term not often used but which should be accurately applied is pseudo reference electrode.

What this means is that the reference electrode is only a reference electrode under certain conditions  of stable chloride concentration.  In many applications chloride can be considered to be stable and repeatable, for example the chloride concentration in blood, plasma, serum, interstitial fluid etc the chloride concentration is around 135 to 150 mM. In other applications such as urine analysis, water testing, food testing etc, the chloride concentration maybe unknown and maybe a variable. The issue  is that a silver/silver chloride reference electrode has a potential that is effected by the sample's chloride concentration,  this is shown in the adjacent image.

The effect of having a pseudo reference electrode is that sensors based on amperometry potentiometry, voltammetry, etc many not function as expected if the chloride concentration is unknown and variable.

THE SOLUTION

ZP has developed a reference electrode that it can apply to its standard products that is insensitive to changes in chloride concentration, please see adjacent image.

Zimmer and Peacock has the world's only off-the-shelf platform for analysing sweat, be it glucose, lactate, sodium, oxygen, chloride or pH. In the adjacent video we show you a configuration for collecting sweat and moving the sweat over a sensor.

Thank you for talking to us at BioMed Devices San Jose 2018.

At the conference we spoke about sensors for potassium, sodium, pH, glucose, lactate, oxygen, etc.

We talked about wearable sensors and detecting analytes in urine, plasma, sweat and blood.

If you have any questions regarding Zimmer and Peacock please don't hesitate to contact us.

At Zimmer we believe that ion sensors including sodium, potassium and pH are important sensors, that is why we are delighted to expand our range with a chloride sensor.

The adjacent picture is the front side and back side of a ZP sensor, when using these sensors it is important that the connector you use does not cause a short between the front side and backside. If you are planning to use these sensor in a potentiometric mode you of course need to make electrical connection with the working/sense electrode, you can then choose to use the reference or counter electrodes as your reference or short the counter and reference together and have them combined as the reference electrode.

At Zimmer and Peacock we are here to help our clients and customers. This week we had an enquiry about the EIS and potentiostats of Zahner that ZP distributes in the Nordics and UK.

In the short post below we have answered some of the recent questions we received. 

1. The Zahner system can be controlled by windows7/8/10-PC, though the Win10 machine is not supplied';this means that if you have a Win10 machine you can run the software.

2. Some of the Zahner potentiostats are advertised as having Controlled voltage: ±15 V / ±5 V, what this means is that you can choose to operate the instrument  at ±15 V or ±5 V; you will use the ±5 V voltage often in  applications like the Gratzel cell etc, whilst you will use the ±15 V setting in power applications like batteries and fuel cells. Switching between ±15 V or ±5 V is an option in the software.

3.What is the difference between the compliance voltage and the controlled voltage? Often in an electrochemical cell we will have the working electrode, the counter electrode and the reference electrode. The electrochemist is often interested in controlling the voltage at the working electrode (called controlled voltage), but what we as electrochemists sometimes over look is that the potentiostat then applies another voltage to the cell at the counter electrode called the compliance voltage. The reason that the potentiostat applies this compliance voltage at the counter electrode is because the rate of reaction at the counter electrode needs to be as fast as the rate of reaction/current at the working electrode. So in summary the controlled voltage is what we apply at working electrode, whilst the compliance voltage is what the potentiostat applies to the counter electrode to ensure the rate of reaction at the working electrode is as fast as it need to be.

4. Zahner instruments come with extra slots for additional hardware modules, these slots can be used for additonal cards like the TEMP/U and the PAD4. For example the TEMP/U allows for the measurement of parameters such as pH, temperature etc within the electrochemical cell, whilst teh PAD4 is often used to measure 4 electrochemical cells that are in a battery or fuel cell stack.

5.The PAD4 is useful in applications where you have for example a series of electrochemical cells stacked together to form a battery. The Zahner potentiostat would allow you to measure the impedance across the entire battery, but if you want to know how individual cells within the batter are performing you can use the PAD4 to measure up to 4 cells within the stack, of course the more PAD4 cards you use the more cells within a stack you can measure.

6 The PP211 is often supplied with Zahner CIMPS systems, this is because the Zahner CIMPS system has a light source and the P211 is the 'power supply  to that light source.

ZP se presenta como uno de los patrocinadores del Congreso Columbiano de Electroquímica.

ZP es uno de los líderes mundiales en tecnología para electroquímicos: electrodos impresos, potenciostatos, etc.

Por favor no dude en contactar con nosotros para más detalle

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Question - What do you get when you add one admin, one scientist and two engineers?

Answer - A much stronger team.

At Zimmer and Peacock we have been busy growing, welcome to our new team members.

This week Zimmer and Peacock were asked to measure the pH of cheese, and though a first for us we were able to do it using one of our disposable screen-printed pH sensors.

At Zimmer and Peacock we manufacture a number of sensors, including: glucose, lactate, sodium, potassium, pH, oxygen, chilli hotness, garlic pungency etc. If you are looking for a sensor and it is not on our list please feel free to contact us, of if you have any questions regarding our standard sensors don't hesitate to drop us a line.

At ZP we like to work on technologies that will change the world, and that is why we put so much effort into health, well being, food and agriculture. This week we met with a number of stakeholders to brainstorm how to reduce a global epidemic, i.e. corrosion.

If you come to see Zimmer and Peacock in Horten we will probably take you to see our facility access at USN.

Zimmer and Peacock are delighted to be exhibiting at the Antwerp Maritime Academy on the 1st April as part of their Maritime Corrosion Workshop.

At Zimmer and Peacock we believe in getting our customers and clients to market ASAP, so we are trying to remove every possible barrier; hence why we have such a complete product and information offering around our sensors and products.

This week we have expanded our product portfolio to include calibration/test solutions for our sodium and potassium sensors.

Zimmer and Peacock is a world leading contract developer and manufacturer of biosensors, sensors and medical diagnostics, and so we visited Medica last week to talk to supplier and clients, and understand the direction of the health markets.

At Zimmer and Peacock we know that wearables are the future of biosensors, health and fitness monitoring. We specialise in the contract design and contract manufacture of biosensors and medical diagnostics including wearable sensors and biosensors. Our wearable biosensor capabilities include: glucose, lactate, sodium, potassium, pH, oxygen, etc. Alongside our understanding of the sensor we also have the electronics for both the sensor and the bluetooth communication. 

At ZP we appreciate that the choice of adhesive materials to attach the sensors to the skin is important, and the choice of materials depends on the: application, the skin type, the demographics of the target market, the expected duration of wear.

Clearly an adhesive material has a degree of adhesion, which is not static  with time. The adhesivity can increase with time reaching a maximum before the adhesion begins to decrease; at the same time the skin is also replenishing and so skin cells that we initially in place start to shed, and the adhesive can start to peel away.

The material scientists have a number of levers to pull when selecting or designing an adhesive material for a wearable biosensor/sensor application this included : class of compound, specific compound, thickness of adhesive etc.

In the adjacent video we show four adhesive attached to the same subject, left for 2 hours and then an attempt is made to remove each adhesive, and it is clear that each material has a different degree of tackiness to the skin.

In the adjacent experiment a ZP potassium sensors were tested at three concentrations of 0.1 mM, 1 mM and 10 mM potassium ion concentration. The sensor was tested this way in three consecutive experiments, within a 45 minute period - see adjacent image.

The sensor was taken out of solution between each experiment (trial) and in this study the sensors showed a change between each trial -  see adjacent image.

We zoomed in on the data at 1 mM potassium to understand the drift on the sensors - see adjacent image.

We were able to determine that the potassium sensor showed a change in sensitivity of approximately 6 % per hour when in a constant concentration solution of potassium ions of 1 mM .

We were recently at the Diabetes Technology Conference in Bethesda Maryland, and it was clear that there was a new wave of interest in continuous glucose sensors and monitoring, and so to celebrate ZP has launched our increased capabilities in the CGM space.

Zimmer and Peacock are a world leader in biosensor development and contract manufacturing. We are delighted to be attending TekMar 2018 on the 4 and 5 December in Trondheim, where we will be discussing biosensor for Salmon Farming and other Aquaculture applications.

Zimmer and Peacock were delighted to present our poster and perform hardware demos at the Diabetes Technology Meeting 2018 in Bethesda.

Please feel free to download our poster from this page and click the links to see the range of biosensors and our wearable biosensor platform for continuous glucose monitoring and other wearable biosensor applications.

Please download our DTM poster here.

Zimmer and Peacock launches a new sensor for the rapid and easy determination of garlic and garlic products.

To find out more about ZP click the buttons below.

Zimmer and Peacock are delighted to be highlighted in the University of Oxford Periodic Magazine. The article deals with the Chilli Sensing Technology developed at the Compton Group and how ZP has rapidly taken it to market.

Zimmer and Peacock were recently invited to speak on a  panel for Talent Bank in  Swansea.

As part of the day ZP got to see the future generation of surgeons practicing their skills.

Zimmer and Peacock is sponsoring a research Masters project to develop a novel, smart electrochemical sensor technology for the detection of Cannabidiol (or CBD), a prescription drug. Using the state of the art facilities at Swansea’s Centre for Nanohealth, the MSc scholar will work with top research scientists and academics to develop sensors for testing and purity quality control.

At Zimmer and Peacock we distribute both Micrux and PalmSens as we believe in the best technology for the problem that is being investigated or solved, sometimes this is a combination of parts from both companies.

In the adjacent image we have shown all the parts necessary to go from a MUX8 to a Multi8x-AIO.

Please watch the adjacent video to have a peek behind the scenes at Zimmer and Peacock.

Zimmer and Peacock is a world leading contract biosensor and medical diagnostics company for wearable biosensor, sensors and medical diagnostics, the video shows some of our rapid prototyping services.

Zimmer and Peacock is focused on helping our clients and partners get to marker ASAP with electrochemical sensors suitable for field applications.

For a screen printed electrode to be commercially successful in the field the following FEATURES are important.

1. FEATURE ONE - The sensor must have the potential to be low cost, so to ensure the highest margins.

2. FEATURE TWO - The sensors have to function correctly.

3. FEATURE THREE -The sensors should operate at a low power, with simpler electronics.

It is with these FEATURES in mind that ZP has started to promote the ‘value range’ over our first generation of sensors and electrodes.

In the following sections we discuss why the ZP ‘value’ sensors are superior over the ZP first generation of electrodes.

FEATURE ONE - COST

The ‘value’ sensors are 44 % smaller than the generation one sensors. This means that when manufacturing sensors in processes such as sputtering, flat-bed screen printing, roll-to-roll printing etc one will produce 1.8 times more value sensors for every one ZP sensors.  Clearly the production capacity can be approximately doubled by this simple change with little or no CAPEX expenditure.

ZP also sees the ZP value sensor’s benefits translating into other downfield processes, for example if sensors are functionalized by a digital printing process it is possible to functionalize a sheet of value electrodes and produce  1.8 more sensors before having to do a card/sheet change.

The smaller form factor adds benefits further downstream when it comes to packing, storing and shipping.

ZP does understand that you cannot make a sensor so small that the user can no longer handle the sensors, and so we have surveyed the glucose strip market before coming to the final decision on the value sensor size; we also now have practical experience from our ChilliPot product which is on the market and uses the value sensor form factor. 

FEATURE TWO – CORRECT FUNCTION

ZP employs a number of principles from the glucose strip market and so it is fairly achievable to make microfluidic/capillary fill sensors with electrodes in close proximity to one another and where the sample volumes can be below 1 microliter. 

Whilst it is both a nice feature for the clients to have the ability to use sample volumes as small as 300 nL it does introduce an issue not commonly considered by electrochemists, which is ‘what is happening at the counter electrode?’

In traditional electrochemical thinking what happens at the counter electrode has been mostly ignored based on the following assumptions:

1) ASSUMPTION ONE - The counter electrode has been traditionally large relative to the working electrode.

2) ASSUMPTION TWO - The counter electrode has traditionally been at some distance from the working electrode.

3) ASSUMPTION THREE – Traditionally the solution within the electrochemical cell has been large relative to the electrodes.

The three assumption above are used by electrochemists to say that the counter electrode is not so important when understanding the signals within an electrochemical sensor, but these assumptions are not necessarily valid in very small volumes associated with electrochemical sensors and biosensors which have capillary/microfluidic chambers upon them.

Let’s consider a thought experiment containing an electrochemical assay which operates by applying 650 mV to the working electrode; in this assay the analyte is oxidized at the working electrode, at the counter electrode an equimolar reduction reaction is occurring in parallel with the working electrode reaction.  The reaction at the counter electrode is often not known or fully characterized and can be influenced by a number of parameters including: the concentration of oxygen, the pH, the current driven at the working electrode. 

Therefore, there are at least three variables that govern what maybe happening at the counter electrode, one thing one can often be certain of when using a traditional carbon platinum or gold electrode which is that the counter electrode electrochemical reaction is at best unclear and often unknown.   

The issue is that the unknown products at the counter electrode may diffuse across to the working electrode and so after some seconds the products of reaction at the counter electrode may start to influence the reactions at the working electrode and therefore introduce an otherwise over-looked and uncontrolled contribution to the signal effect, this is schematically.

The diffusion of material from the counter electrode to the working electrode in systems where the electrode spacing is millimeters can happen on the seconds to 10s of seconds time range, and so this event can influence the signal. The observable effects of this diffusion can be numerous, but one possible outcome is an electrochemical feedback loop where the reduction product at the counter electrode diffuses to the working electrode and is subsequently re-oxidized. This re-oxidation in turn causes a further increase in current at the counter electrode which in turn drives further diffusion of reduced material from the counter electrode to the working electrode hence further driving up the current, this is in effect a closed loop electrochemical  feedback system , we illustrate such a scenario in the adjacent figure.

Zimmer and Peacock AS is Norway's leading contract biosensor, wearable biosensor and medical diagnostics company providing contract development and manufacturing services, alongside our standard products.

This week we were showing our technologies and capabilities ranging from exhaled breath collection to the hotness of chilli sensing at the Made in Horten show.