Abstract

PET Microchannel Impedance through two embedded planar microelectrodes

Jean Gamby, Researcher, University of Pittsburgh Medical Center

The purpose of this paper is to show how eliminate impedance contribution of insulated layer in flexible polymer microchip. Measurements were carried out through a polyethylene (PET) channel photoablated having a trapezoidal cross-section shape with a depth of 45 µm, a width of 100 µm and a length of 1,4 cm. The distance separation between both channels is 120 µm center to center. The detection is achieved using carbon ink electrodes, thermally laminated by a polyethylene /polyethylene terephthalate (PE/PET) layer with thickness of 35 µm at 135°C and a pressure of 2 bar. The distance separation in the PET band between the two planar microelectrodes and the main microchannel is equal to 5 µm and the detection surface area per microelectrode is 88 µm x 100µm. Study was carried out by the impedance measurement in alternative mode (ac) through the two microelectrodes at frequency range from 1 MHz to 1 Hz with 0,1 V amplitude, in order to have the electrical behavior of the overall microsystem and to extract the specific microchannel response. The corrected impedance diagrams were plotted by eliminating PET layer impedance contribution from the global microdevice response. This operation allows a clear observation of solution microchannel impedance such as, resistance, capacitance and diffusion phenomenon in microchannel.