Field effect sensors for PCR applications

Abstract

This research focuses on the use of EIS (electrolyte on insulator on Silicon) structure as a detection method for pathogenic DNA binding. The EIS structure (Electrolyte on Insulator on Silicon) provides a novel, label-free and simple to fabricate way to make a field effect DNA detection sensor. The sensor responds to fluctuating capacitances caused by a depletion layer thickness change at the surface of the silicon substrate and also through DNA adsorption onto the dielectric oxide/amino surface. As DNA molecules diffuse to the sensor surface, they are bound to their complimentary capture probes. The negative charge exhibited by the DNA forces negative charge carriers in the substrate to move away from the surface. This causes an n-type depletion layer substrate to thicken and a p-type to thin. The depletion layer thickness can be measured by its capacitance using an HP4284a LCR meter. This experiment is conducted using the ConVolt (constant voltage) approach. Nucleic acids are amplified by an on chip PCR system and then fed into the sensor. The low ionic solution strength will ensure that counter-ions do not affect the sensor measurements. The sensor surface will contain capture probes that will bind to the pathogen. They are held onto the sensor surface by the positively charged amino layer.