Electrical Connections

For making electrical connections to microfluidic chips, Micronit offers a simple but effective solution: the Electrical Connection Kit. The kit can be used in combination with the Micronit chip holder and customized Micronit chips with integrated electrodes. The kit enables easy, plug-and-play connections to your microfluidic chip.

The Electrical Connection Kit contains five cables with a nut and probe (OD=0.76 mm) with receptable at one end, and a standard plug at the other end. The spring point in the probe has a diameter of 0.5 mm and a sharp angle of 70^o.

Specifications

Current rating	3 A
Maximum Voltage DC                                    AC	30 V (handheld use) 60 V (handheld use)
Maximum operating temperature	50 oC
Contact resistance probe	30 mR
Connector      Type	Banana plug
Cable      Length      Color      Wire Size (AWG)	915 mm black 22
Spring probe      Housing - material      Housing - plating      Contact tip - material      Contact tip - plating	phosphor bronze gold beryllium copper rhodium over nickel
Isolation nut      Material      Thread	PEEK 6-32 UNC

The Electrical Connection Kit is specifically meant to be used as laboratory equipment.

Electrical connections can be used for different applications. Three of them will be described below (click on each of them to learn more).

Conductivity measurement

The electrolyte conductivity in the channel can be measured using a planar integrated interdigitated electrode structure. The number of electrode fingers can be tuned in order to obtain for example a cell constant of approximately 1 cm^-1, which is comparable to conventional conductivity cells. By increasing or decreasing the number or size of the electrode fingers other cell constants can be reached.

For special applications such as end column conductivity detection on capillary electrophoresis chips or chromatography chips the size of the electrode area is usually very small in order not to affect the separation resolution adversely. With space for only a couple of finger electrodes this will result in a larger cell constant. 

Heating

Fluids can be heated using an integrated resistive heating element made from platinum. Locally high temperatures of several hundred degrees Celsius can be created within a couple of seconds using safe to use low voltages. For a homogeneous temperature across a large area of the chip the use of a transparent layer of electrically conductive ITO is usually advisable.

The integrated resistors can also be used to measure temperature, but it should be noted that there is some variation in the room temperature resistance from chip to chip and the temperature coefficient is not necessarily the same as for industrial Pt100 sensors. Sensors should therefore be individually calibrated.

Cell Manipulation

With electrodes integrated in the chips a range of in vitro and ex-vivo cell-based applications can be conducted. Genetic modification of cells on a chip is generally much more efficient than bulk methods. Lab-on-a-chip makes well-controlled single cell manipulation possible, thanks to the small and accurate dimensioning microtechnology offers. In addition, microtechnology is very suitable for scaling up to bulk cell production.

The integrated electrodes can also contribute to measuring the effect of drugs on cells. Before starting therapy, it can for example be determined which medication is the most effective to treat cancer, only using a few of the patient's own cells.

The applications described above are just a few examples of what is possible with electrode integration in lab-on-a-chip. Contact us to discuss the various possibilities we have for your application.