Biosensor based on the field-effect transistor (FET) with an underlap region in one side of the gate has high sensitivity and high probability of biomolecules binding. However, the underlap region presence results in lesser gate control over the channel, leading to lower device characteristics control. In this paper, the channel's grading has been employed in FET with an underlap region in the middle of the gate for label-free biosensing application. Surface potential and threshold voltage models are proposed to analyze its effectiveness in sensing DNA and neutral biomolecules. The introduction of DNA in the underlap area causes hybridization, which changes the biosensor's electrical characteristics due to dielectric and charge modulation and is used as a sensing matrix. The results reveal that the proposed biosensor is not only highly sensitive but also yields improved circuit performance. The analytical findings are verified by using TCAD simulation data. This study helps in the design of a new label-free, ultra-small, and highly sensitive biosensor.

基于场效应晶体管（FET）的生物传感器在栅的一侧具有下重叠区，具有高灵敏度和高生物分子结合可能性。但是，存在重叠区域会导致对通道的栅极控制较少，从而导致较低的器件特性控制。在本文中，该通道的分级已在FET中采用，栅极中间有一个重叠区域，可用于无标签的生物传感应用。提出了表面电势和阈值电压模型来分析其在检测DNA和中性生物分子中的有效性。将DNA引入重叠区域会引起杂交，这种杂交会由于介电和电荷调制而改变生物传感器的电特性，并被用作传感矩阵。结果表明，提出的生物传感器不仅高度灵敏，而且产生了改进的电路性能。通过使用TCAD仿真数据来验证分析结果。这项研究有助于设计一种新型的无标签，超小型，高灵敏度的生物传感器。