Chips for Electrical Impedance Spectroscopy - Top connect

SKU
11001552
Availability:
In stock
€1,095.00

per pack of 2

Pack of two Chips for Electrical Impedance Spectroscopy (EIS) measurements. 

 

Introduction to EIS Combined with Microfluidics

In the Electrical Impedance Spectroscopy (EIS) chip, microfluidics transport a medium that can contain cells or particles over a collection of electrodes. One set of electrodes contains an excitation signal (typically an accumulating current), while the second set of electrodes registers the effect of the cells or particles passing by on the signal. Impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit. In general, it depends on the frequency of the sinusoidal voltage. A passing cell or particle causes a difference in impedance, allowing for counting. However, the impedance difference also provides information about the cell or particle itself, acting as a sort of fingerprint that can be used to distinguish cells or particles with specific properties. The frequency of the excitation signal used has an influence on the ability to distinguish cells or particles.

Application Possibilities.

This chip, equipped with a flow channel and electrodes for Electrical Impedance Spectroscopy (EIS)-based measurements, aims to explore the potential of Electrical Impedance Spectroscopy for your own application. EIS is already commercially applied as a measurement technique in the following areas:

  • Cell and particle counting and characterization, which is an important aspect of flow cytometry.
  • Bacterial counting in (drinking) water.
  • Counting of poles in air.

The Chip

The chip is a hermetically bonded triple-layer device:

  • The top layer is a glass layer with a thickness of 700µm and contains, besides holes and openings, a set of Pt-electrodes.
  • The middle layer consists of a 30µm dry film resist layer and contains the side walls of the channel.
  • The bottom layer also contains a set of Pt-electrodes.

See the drawing for more details.

In total, the chips contain four sets of two electrodes (eight individual electrodes):

  1. Inlet side, top side of the channel
  2. Outlet side, top side of the channel
  3. Inlet side, bottom side of the channel
  4. Outlet side, bottom side of the channel

Each electrode set has the following structure:

What do you need to get started?

  • Pack of chips
  • Fluidic Connect Pro for EIS chips (15x15mm) or a set of EIS insert when a chip holder is already available.
    (8 cable assemblies are included with the holder)
  • Pumps—basic syringe pumps should work, but pressure-based pumps can offer more control. When both the inlet and outlet are pressurized, the flow can be stopped instantly.
  • Zurich instruments HF2LI
  • Zurich instruments Current Aplifier HF2TA 
  • (Inverted) microscope or suitable USB microscope.
  • Computer with optional pump control software and LabOne (from Zurich Intruments)

Customizations

Existing commercial applications use a range of different chip designs depending on what's measured. It's likely that for the most optimal measurement result, some application-specific customization might be required. We are happy to help with further customizations as part of your product development.

 

More Information
Unit of measurementpack of 2
Chip thickness1.4mm
Number of inlets1
Number of outlets1
Channel width30µm
Electrode materialPlatinum
Icon Label Description Type Size Download
pdf Drawing EIS - Top Connect Chip pdf 89.1 KB Download
Customer Questions
How do I clean my chips?
One simple but very effective way to clean a microchip is to flush an alkaline solution through the channels. A solution of 1 M sodium hydroxide in water works well, but a lower concentration might also be sufficient. If traces of the cleaning solution remain inside the chip after cleaning, rinse with water or ammonia. Further, plastic parts should not be exposed to alkaline solutions.
To remove particulate matter from your chip, a water bath with ultrasonic agitation can be used, preferably while flushing a watery solution through the channels.
Glass microchips can be heated (e.g. 400°C) causing any organic material on the glass surface to degrade. Try to use lower temperatures first because burning the content could make it stick. Make sure you only heat the glass chip and not the plastic parts around it.
Concentrated sulfuric acid works well to dissolve organic material, such as fibres, that are difficult to remove with alkaline solutions. Always keep in mind that you are working with extremely corrosive material.
Please note that chips that were coated by Micronit have different guidelines for cleaning!
I need a pumping system for my setup. Which one do you recommend?
We recommend using a high precision pumping system. Regular syringe pumps often don't work very well for droplet generators. There are several high precision pumping systems on the market that work with different pumping principles. To name one, we'd like to mention that we have had positive experiences with the equipment Fluigent offers: https://www.fluigent.com/  
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