Kutova O. Biomolecular and chemical sensors based on silicon field effect structures

Ph.D. thesis on specialty for candidate’s degree of technical science 05.11.17 – biological and medical devices and systems. – National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, 2019. This work is dedicated to learning in complex, analyzing the characteristics of sensor’s structures based on silicon field effect structures, improving the methods of analysis and fabrication of such structures for chemical and biomolecular compounds detections. Several sensors modifications based on silicon field effect structures for the detection of aqueous solutions of organic (C-reactive protein, beta-lactoglobulin) and inorganic medium (H2O2, NaCl) was proposed in this manuscript. Also, pH-sensor was proposed. To create a pH sensor, a MOSFET transistor with a subgate dielectric CeO2 was used. The pH sensitivity of the sensor was practically close to the maximum possible – 58.5 mV/pH, and the stability of the results was ~ 98.65%. For the H2O2 sensor, the rear side of MOSFET in combination with the hydrogen peroxide catalyst was used as a working area. The use of a porous structure (was formed by metal-assisted chemical etching) in combination with Pt nanoparticles, as a catalysts of H2O2, has allowed to increase sensitivity of the sensor by almost 30%. For the first time, a multilayer structure for the C-reactive protein detection was proposed, using a sensor based on the CeO2 ISFET as a sudgate dielectric. The developed sensor has the limit of detection at 0.1 mg/L and the sensitivity at 290 mV/(mg/L). For this analysis only 20 μl of the reagent and about 1 min of time are needed. Sensor’s structure with cerium dioxide gate dielectric with improving detection method for the dynamic investigation of beta-lactoglobulin, the main milk allergen, was proposed and developed. The existing method requires a long time (~1,5 hours), and the proposed method allows identifying the presence of beta-lactoglobulin in just a few minutes.