Design and Fabrication of Thin-Film Transistor-based Microcantilever Biosensor
Date Issued
2010
Date
2010
Author(s)
Lin, Ping-Yen
Abstract
As elderly population for most developed countries continues to grow, and consume healthcare funds, an increasing proportion of gross domestic product (GDP) is absorbed by escalating healthcare costs. As a result, introduction of the telecare/telemedicine technology proves to offer advantages of fewer emergency admissions, and dramatically lower care cost per patient through improved condition management. To fulfill the service of rapid diagnostics at home, miniaturization and portability of medical instruments are required for specific healthcare of post-hospital follows-up.
This study utilizes thin-film transistor (TFT) as a sensing transducer to convert induced stresses of a microcantilever into an electrical signal. The TFT-based microcantilever was made by micro-electromechanical system (MEMS) fabrication technology. The mobility of polysilicon TFT fabricated in this work was measured to be 22~25 cm2/Vs. This study has proven to reveal significant increase of drain current of released microcantilevers in comparison with the un-released devices. Meanwhile, significant change of output signal of transverse n-channel direction with respect to strain was found to be five times greater than that of longitudinal one. Higher gate voltage of 8 volts resulted in current leakage to the suspended thin-film transistor. It was also found that the TFT drain current sensitivity of the chip was measured to be 0.08 μA/μm.
This study pioneered to design and fabricate poly-Si TFT onto a suspended microcantilever. Integration of existed integrated circuits is highly feasible and compatible with the TFT microcantilever. As a result, the miniaturized and integrated microcantilever for biosensors is highly anticipated to be realized in future.
Subjects
Microcantilever
Thin-film transistor (TFT)
Surface stress
Micro-electromechanical system (MEMS)
Type
thesis
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