Shivendra Upadhyay completed PhD thesis on Design of Indium Arsenide nanowire sensors for pH and biological sensing and low temperature transport through p-doped Indium Arsenide nanowires

About the thesis

With the goal of real time electrical detection of chemical and biological species, nanowires have shown great promise with high sensitivity due to their large surface to volume ratio. While the focus of such electrical detection has shifted to one dimensional semiconductor nanostuctures, Silicon remains the primary material of choice. This research is about investigating Indium Arsenide nanowires as alternative platform for sensing charged species - chemical and biological, in solution.

Starting with nanowires grown via molecular beam epitaxy in an ultra-high vacuum chamber, we discuss the fabrication of nanowire transistors using UV and electron beam lithography as well as the steps to encapsulate the nanowire transistors into a sensor. Several iterations of experiments demonstrating pH sensitivity of the NW sensor are presented.

Having established and tested a stable sensing platform via pH sensing, we apply the same to a more complex system - proteins. The sensing protocol involves the functionalization of the sensor surface with a receptor protein followed by the addition of the protein of interest. Sensor response to oppositely charged proteins is used to confirm the sensitivity of the sensor to the protein charge.

https://qdev.nbi.ku.dk/student_theses/pdf_files/PhDThesis_Upadhyay.pdf