| Biosensor,currently a multi-disciplinary overlapping research area,is full of innovation and vigor.Thin film transistor(TFT)biosensors have a series of advantages over other types of biosensors,such as smaller volume,easier integration,stronger anti-interference and so on.However,most reported TFT biosensors have a structure with the semiconductor channel directly embranced by the biological detecting area,which leads the semiconductor layer to be affected by the biological/chemical solution and thus shorts the service life of the TFT devices.On this context,segregated-type IGZO-TFT biosensors were successfully developed to detect the mouse IgG(immune globulin)and anti-rabbit IgG in this thesis.The main results can be summarized as follows.1.Segregated-type double-gate IGZO-TFT biosensors were designed and fabricated,and their electrical response on biomolecules(such as mouse IgG)was investigated.Firstly,double-gate IGZO-TFTs with an extended-top-gate structure were well-designed and then fabricated via the four-step-mask method,combined with magnetron sputtering,electron beam evaporation and post annealing process.The optimized device presented excellent transistor properties,with a subthreshold voltage swing of 172 mV/decade,a current on/off ratio of ~ 5.3 × 107,a threshold voltage of 6.4 V and a saturation mobility of 25 cm2V-1s-1.Secondly,the modification of goat-anti-mouse IgG biological molecular membrane on the Au film(surface of the sensing pad)was finished through aldehydes and covalent crosslinking steps,and then characterized by confocal fluorescent microscopy.Finally,a segregated-type double-gate IGZO-TFT biosensor combined the above-mentioned TFT and sensing pad was successfully constructed to detect mouse IgG(2 mg/m L).2.Segregated-type IGZO electric-double-layer TFT biosensors were designed and constructed,and their electrical response on biomolecules(such as goat-anti-rabbit IgG)was investigated.Firstly,IGZO electric-double-layer TFTs were fabricated by one-step-mask method,combined with plasma enhanced chemical vapor deposition,magnetron sputtering and electron beam evaporation.The optimized TFT showed a superior performance with a big current on/off ratio of 106,a low subthreshold swing of 100 mV/dec and a low working voltage less than 1.5 V.The device also showed good stability and anti-interference.Secondly,the rabbit IgG was decorated on the Au film(surface of the sensing pad)through the esterification,covalent crosslinking and other correlated steps.The density and uniformity of the decorated rabbit IgG were monitored by atomic force microscope.Finally,segregated-type IGZO electric-double-layer TFT biosensors were fabricated.It worked under an ultra-low voltage and showed a linear relationship in the region of 1.6 ~ 368 fg/mL in detecting goat-anti-rabbit IgG.The low limit of detection is down to 1.6 fg/m L,which is better than those reported in literatures.The above-mentioned biosensors allow the separation of TFT device from the chemical/biological environment,hence with ease in packaging the TFT device,which can improve the stability and lifetime of the TFTs.And it permits one TFT device to be connected to different kinds of sensing pads,which makes it possible to realize plug-in-card-type multifunctional biochemical sensors(one device to detect several kinds of biomolecules). |
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