Field effect sensors for biosensing
This research focuses on the use of EIS (electrolyte on insulator on Silicon) structure as a detection platform for 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. In this paper we present the fundamentals of the Capacitance-Voltage plot technique and how it can be used a method for detecting DNA binding and surface charge transits. The CV plot is a widely used technique in the microelectronics industry for characterizing and profiling capacitor devices. It is mainly used to test the quality of these devices and give an indication of failing processing conditions. Its high sensitivity and ability to provide a wealth of information makes it a suitable choice for our research . We also looked at using 2 types of amino layers and compared their effectiveness as DNA adhesives based on surface charge. The two types we chose to investigate were Poly-L-Lysine and 3-Aminopropylthioxysilane. Their compounds are quite similar in nature in that they contain a NH2 terminated group which is easily protonated in physiological buffers. PolyLysine and APTES are both commonly used in labs to coat slides for adhering cells and also used as monolayer linkers for tethering further compounds. PolyLysine tends to be more expensive than APTES, but safer to use since it isn't as corrosive as APTES. Our results show that APTES was a suitable choice for our experiments.
Biomedical Applications of Micro- and Nanoengineering II Proc.