Design and Fabrication of Thin-Film Transistor-based Microcantilever Biosensor
|Keywords:||微懸臂樑;薄膜電晶體;表面應力;微機電;Microcantilever;Thin-film transistor (TFT);Surface stress;Micro-electromechanical system (MEMS)||Issue Date:||2010||Abstract:||
本研究針對以力學為基礎的微懸臂樑生物感測器進行探討，並採用多晶矽薄膜電晶體做為訊號轉換機制，訊號轉換時不會與環境介質接觸。本研究利用半導體及微機電製程技術將薄膜電晶體製作於微懸臂樑上，完成之多晶矽電晶體電子遷移率為22~25 cm2/Vs。本研究探討了微懸臂樑懸浮前後電晶體電性的改變，懸浮後的電晶體電性有所提升，但在閘極電壓超過8V後電晶體因漏電而失去標準電性。其中電晶體通道方向垂直於微懸臂樑時受應變時的電流變化量為平行時的5倍左右。應力變化與電晶體之電性特性研究上，利用探針下壓微懸臂樑量測電晶體飽和電流變化之實驗結果顯示，本感測器之電晶體飽和電流靈敏度為0.08 μA/μm。
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.
|Appears in Collections:||應用力學研究所|
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