Ultra-thin silicon membrane as a sensitive substrate for active bioscreening

Abstract

This research article concentrates on evaluating ultra-thin silicon membrane as a candidate material for monitoring biophysiological cell events. Electrochemical Impedance Spectral (EIS) studies were used to extract and explain the reduction in substrate parasitics when compared to commonly used plain Si substrate. A two electrode system comprising planar interdigitated gold transducers (IDTs) immobilized with human endothelial cells (HUVEC) buffered in Hank's Blank Salt Solution (HBSS) formed the electrochemical cell. Impedance measurements was carried out using a Cascade MicroChamber™ probe station attached to an Agilent 4294A Impedance Analyzer over a frequency ranging from 100 Hz to 1 MHz. The optimized cell constant of the IDT was found to be 10.1 m-1 tailored for low impedance biodiagnostics. Extraction of EIS parameters from cell capacitance plot (Bode Magnitude) as well as extrapolation suggested five orders of magnitude reduction in parasitics when compared to plain Si substrate. The HUVEC (Human Umbilical Vein Endothelial Cells) capacitance and resistance was found to be around 3.33 nF and 35.6 KΩ respectively for the membrane device of equal IDT width and spacing. © Springer-Verlag 2007.