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Title: Microfabricated acoustic sensors for the detection of biomolecules
Author: Weckman, Nicole Elizabeth
ISNI:       0000 0004 7228 4292
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2018
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MEMS (Microelectromechanical Systems) acoustic sensors are a promising platform for Point-of-Care biosensing. In particular, piezoelectrically driven acoustic sensors can provide fast results with high sensitivity, can be miniaturized and mass produced, and have the potential to be fully integrated with sample handling and electronics in handheld devices. Furthermore, they can be designed as multiplexed arrays to detect multiple biomarkers of interest in parallel. In order to develop a microfabricated biosensing platform, a specific and high affinity biodetection platform must be optimized, and the microfabricated sensors must be designed to have high sensitivity and maintain good performance in a liquid environment. A biomolecular sensing system that uses high affinity peptide aptamers and a passivation layer has been optimized for the detection of proteins of interest using the quartz crystal microbalance with dissipation monitoring (QCM-D). The resulting system is highly specific to target proteins, differentiating between target IgG molecules and other closely related IgG subclasses, even in complex environments such as serum. Piezoelectrically actuated MEMS resonators are designed to operate in flexural microplate modes, with several modes shown to be ideally suited for fluid based biosensing due to improved performance in the liquid environment. The increase in quality factor of these MEMS microplate devices in liquid, as compared to air, is further investigated through the analytical and finite element modeling of MEMS fluid damping mechanisms, with a focus on acoustic radiation losses for circular microplate devices. It is found that the impedance mismatch at the air-water interface of a droplet is a key contributor to reduced acoustic radiation losses and thus improved device performance in water. Microplate acoustic sensors operating in flexural plate wave and microplate flexural modes are then integrated with a fluidic cell to facilitate protein sensing from fluid samples. Flexural plate wave devices are used to measure protein mass adsorbed to the sensor surface and initial results toward microplate flexural mode protein sensing are presented. Finally, challenges and areas of future research are discussed to outline the path towards finalization of a sensing platform taking advantage of the combination of the sensitive MEMS acoustic sensor capable of operating in a liquid environment and the specific and high affinity biomolecular detection system. Together, these form the potential basis of a novel Point-of-Care platform for simple and rapid monitoring of protein levels in complex samples.
Supervisor: Seshia, Ashwin Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Biosensors ; MEMS ; Acoustic resonator ; Quality Factor ; QCM-D