study of interfacial phenomena for bio/chemical sensing application
Open Access
- Author:
- Min, Hwall
- Graduate Program:
- Electrical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- December 06, 2013
- Committee Members:
- Srinivas A Tadigadapa, Dissertation Advisor/Co-Advisor
Srinivas A Tadigadapa, Committee Chair/Co-Chair
Jerzy Ruzyllo, Committee Member
Theresa Stellwag Mayer, Committee Member
David Lawrence Allara, Special Member - Keywords:
- quartz
resonator
quartz crystal microbalance
biosensor
chemical sensor
protein adsorption
RSA
ionic liquid
pattern recognition - Abstract:
- This work presents the fundamental study of biological and chemical phenomena at the interface and (bio)chemical sensing applications using high frequency resonator arrays. To realize a versatile (bio)chemical sensing system for the fundamental study as well as their practical applications, the following three distinct components were studied and developed: i) detection platforms with high sensitivity, ii) novel innovative sensing materials with high selectivity, iii) analytical model for data interpretation. 8-pixel micromachined quartz crystal resonator (microQCR) arrays with a fundamental resonance frequency of 60 – 90 MHz have been used to provide a reliable detection platform with high sensitivity. Room temperature ionic liquid (RTIL) has been explored and integrated into the sensing system as a smart chemical sensing material. The use of nanoporous gold (np-Au) enables the combination of the resonator and surface-enhanced Raman spectroscopy for both quantitative and qualitative measurement. A statistical model for the characterization of resonator behavior to study the protein adsorption kinetics is developed by random sequential adsorption (RSA) approach with the integration of an effective surface depletion theory. The investigation of the adsorption kinetics of blood proteins is reported as the fundamental study of biological phenomena using the proposed sensing system. The aim of this work is to study different aspects of protein adsorption and kinetics of adsorption process with blood proteins on different surfaces. We specifically focus on surface depletion effect in conjunction with the RSA model to explain the observed adsorption isotherm characteristics. A number of case studies on protein adsorption conducted using the proposed sensing system has been discussed. Effort is specifically made to understand adsorption kinetics, and the effect of surface on the adsorption process as well as the properties of the adsorbed protein layer. The second half of the dissertation focuses on chemical sensing and biosensing applications. For chemical sensing, we describe the characteristics of room temperature ionic liquid (RTIL) as a chemical recognition material and integrate it into the quartz crystal resonator arrays to realize chemically selective microsensor arrays. The quartz crystal resonator array integrated with RTIL doped ionomer is then used to detect the presence of volatile organic compounds (VOCs) and to qualitatively and quantitatively discriminate the composition of VOC mixtures. For multianalyte discrimination, we explored the linear discriminant analysis (LDA) technique. For biosensing application, nanoporous gold (np-Au) fabricated by selectively dealloying Ag/Au alloy, is integrated onto the sensor array as an active Raman substrate to provide a special structure for enhancement of Raman signal. Using thiol based biomolecular functionalization in combination with the quartz crystal resonator array based gravimetric sensing and surface-enhanced Raman spectroscopy (SERS) based molecular identification, both quantitative and qualitative (dual-mode) sensing has been achieved. The use of nanoporous gold electrode enables label-free biomolecular fingerprinting via SERS. 24-mer oligonucleotide binding reaction was investigated to prove the usefulness of np-Au for a possible dual mode sensing application using the proposed sensing system and SERS.