| MS TSA Meeting

Name of the Speaker: Mr. Kaustav Dutta (EE19S033)
Guide: Prof. Enakshi Bhattacharya
Co-Guide: Prof. Nandita Das Gupta
Venue: ESB-210B (Conference Hall)
Online meeting link: https://meet.google.com/vdu-fvzn-vev
Date/Time: 28th May 2024 (Tuesday), 3:00 PM
Title: Silicon Carbide MEMS Resonators for mass sensing and detection of Coronavirus

Abstract :

Designing a molecule-specific analyte detection technology with high sensitivity is crucial in the biomedical field. Therefore, finding a robust, biocompatible material that can be used to develop a miniaturized sensing device is desirable. Several materials, including silicon (Si), Silicon Nitride, and polysilicon, have been used to create ultra-miniature structures. Biological sensors comprising Si or Si3N4 cantilevers were developed and successfully detected antibodies, bacteria cells, and single virus particles. With increased downscaling trends, these traditional materials exhibit various limitations that affect the sensitivity of the fabricated structure. So, there is a need for a superior material that can overcome these limitations and be biocompatible. Initial computational analysis favored SiC over conventional materials, owing to its remarkable mechanical robustness, high thermal conductivity, and chemical inertness.

To demonstrate the superiority of SiC sensors practically, the membrane dimensions were first optimized in COMSOL software. With the simulated design, the resonators were fabricated using single crystalline N-type 4H-SiC by timed Inductively Coupled Plasma-Reactive Ion Etching (ICP-RIE). The etch recipe was optimized to reduce surface roughness, and a 3-layer mask material capable of withstanding the etching conditions was deposited. The resonance frequencies of the membrane were characterized using a dynamic vibration method, and the results were found consistent with COMSOL simulations. To evaluate the mass detection capability, yeast solution was allowed to physically adsorb on the membrane, resulting in a regular shift in resonance frequency for every mode. The membrane resonators demonstrated a mass sensitivity of 11.93 Hz/ng, which was in close agreement with the analytical value. The original resonance frequencies of the resonator were recovered by removing the physically adsorbed yeast chemically. Finally, the membranes were functionalized and exposed to Covaxin. It was able to detect a mass attachment as low as 38 ng. These results validate SiC's superiority as a fabrication material for MEMS sensors and also establish a strong foundation for a more reliable, simple, yet robust sensor, overcoming limitations associated with traditional materials.