In this study, we report a pH-responsive hydrogel-modified silicon nanowire field-effect transistor for pH sensing, whose modification is operated by spin coating, and whose performance is characterized by the electrical curve of field-effect transistors. The results show that the hydrogel sensor can measure buffer pH in a repeatable and stable manner in the pH range of 3–13, with a high pH sensitivity of 100 mV/pH. It is considered that the swelling of hydrogel occurring in an aqueous solution varies the dielectric properties of acrylamide hydrogels, causing the abrupt increase in the source-drain current. It is believed that the design of the sensor can provide a promising direction for future biosensing applications utilizing the excellent biocompatibility of hydrogels.

Accurate monitoring of blood glucose levels is crucial for the diagnosis of diabetes patients. In this paper, we proposed a simple “mixed-catalyzer layer” modified silicon nanowire field-effect transistor biosensor that enabled direct detection of glucose with low-charge in high ionic strength solutions. A stable screening system was established to overcome Debye screening effect by forming a porous biopolymer layer with polyethylene glycol (PEG) modified on the surface of SiNW. The experimental results show that when the optimal ratio (APTMS:silane-PEG = 2:1) modified the surface of silicon nanowires, glucose oxidase can detect glucose in the concentration range of 10 nM to 10 mM. The sensitivity of the biosensor is calculated to be 0.47 μAcm−2mM−1, its fast response time not exceeding 8 s, and the detection limit is up to 10 nM. This glucose sensor has the advantages of high sensitivity, strong specificity and fast real-time response. Therefore, it has a potential clinical application prospect in disease diagnosis.

In this work, a silicon nanowire field-effect transistor (SiNW FET) device was developed and applied to pH sensing. A hydrogel was synthesized by radical polymerization as the dielectric and functional layer of SiNW FET. The spin coating process of the hydrogel was defined through different rotating speed. The results revealed that the suitable glue mixing process was determined to be 500 rpm/min at low speed and 4500 rpm/min at high speed. We demonstrated the effect of pH solutions on the sensitivity of the SiNW FET sensor modified by hydrogel. The SiNW FET sensor was used to detect a solution pH ranging from 5 to 11, with the response current increasing stepwise as the pH value increased. Compared with SiNW FET, the hydrogel-coated SiNW FET had higher sensitivity and time response rate for pH sensing. The obtained results demonstrated that modification of hydrogels can significantly increase the pH sensing properties of SiNW FET.