Piezoelectric Plate Sensor for Isolation-free and Amplification-free Detection through an Innovative Combustion-Free Aqueous Materials Synthesis Route

Abstract

Piezoelectric plate sensor (PEPS) is a unique sensor platform developed in Shih and Shih laboratory capable of direct, in situ genetic detection with polymerase chain reaction (PCR) sensitivity and specificity but without the need of gene isolation or amplification. The heart of the PEPS technology is a highly piezoelectric lead magnesium niobate-lead titanate (Pb(Mg1/3Nb2/3)O3)0.65-(PbTiO3)0.35 (PMN-PT) freestanding film. The difficulty and complexity of the synthesis processes for the lead magnesium niobate (PMN) power rendered PEPSs not reproducible. The goal of this thesis is to investigate the aqueous synthesis processes of PMN powder to achieve reproducible PEPSs for isolation-free and amplification-free genetic and immune- detections. The most challenging part of the initial PMN powder synthesis was a combustion step as a result of using ethylene glycol as the medium. The combustion step made the PMN powder finer, essential for making the freestanding film from which PEPSs were made. However, combustion also made the process uncontrollable and difficult to obtain reproducible PEPSs. In this study, we have successfully circumvented the combustion process and achieved similarly fine PMN powder through (1) stringent control of the aqueous synthesis process, (2) mechanical particle size reduction, and (3) creative two-step heating process to crystallize the PMN powder at the same crystallization temperature. The repeatability of these steps and reproducibility of the PEPSs sensors are characterized by X-ray diffraction, particle size measurements, Scanning electron microscopy (SEM) examination sintering of the freestanding film, and the temperature stability and detection performances of the PEPSs. Results showed that the newly fabricated PEPSs made by the new aqueous synthesis routes detected anti-Tn antigen IgM in serum at a concentration 25,000 times lower than the comparing ELISA and detected DNA at 60 copies/ml as comparable to the PEPSs made from the combustion method. We further carried out hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA detection in simulated sera in 30 min without isolation and amplification to illustrate the reliable performance of these newly fabricated PEPSs.Ph.D., Biomedical Engineering -- Drexel University, 201