A high-performance dual in-plane-gate potassium ion-sensitive field-effect transistor with a C4F8 plasma-treated ITO extended gate

• Published in: Sensors and actuators. B, Chemical Chemical, 2025-03, Vol.426, p.137033, Article 137033
• Main Authors: Li, Zehao, Jing, Weixuan, Gao, Weizhuo, Yang, Zhenwei, Zhou, Fan, Han, Feng, Mao, Qi, Zhao, Libo, Yang, Zhaochu, Jiang, Zhuangde
• Format: Article
• Language: English
• Subjects: C4F8 plasma treatment; Capacitive coupling ratio; Dual in-plane-gate; Ion-sensitive field-effect transistor; K+ binding site
• ISSN: 0925-4005
• DOI: 10.1016/j.snb.2024.137033

In this paper a dual in-plane-gate (DIPG) potassium ion-sensitive field-effect transistor (K+-ISFET) with a C4F8 plasma-treated indium-tin oxide extended gate (ITO EG) was proposed. The main in-plane gate (IPG1) and the secondary in-plane gate (IPG2) were symmetrically placed on the outside of the drain and source of field-effect transistor (FET) respectively, and the widths of both IPG1 and IPG2 were regulated. Via lift-off process the IPG1, IPG2 and the basic components of the FET were fabricated on the bottom-gate oxide, and with C4F8 plasma treatment the contact angle (CA) of the ITO EG was tailored. It is found that the IPG2 reduces the quantity of the charges stored between the floating gate and the channel layer, which diminishes the bottom-gate oxide capacitance and improves the capacitive coupling ratio of the FET. The larger the CA of the ITO EG is, the less the surface area of the K+-selective membrane (K+-ISM) obtained from drying the K+-ISM mixture, hence the higher the density of K+ binding sites on the surface of the K+-ISM. With the areas of both IPG1 and IPG2 as well as the CA of the ITO EG optimized, the amplification factor, sensitivity, both hysteresis voltage and drift rate for sensitivity of the DIPG K+-ISFET were determined to be 69.1, 3590 mV/dec, 2.3 %, and 9.1 % respectively. Moreover, the DIPG K+-ISFET reliably determines the K+ concentrations in artificial sweat, artificial saliva, and pond water samples. These results benefit the sensitive detection of Na+, Ca2+, and NO3- concentrations in real complex samples. [Display omitted] •K+-ISFET with IPG1 and IPG2 was proposed and ITO EG was treated by C4F8 plasma.•IPG2 improves the capacitive coupling ratio of the FET.•C4F8 plasma treatment enlarges density of K+ binding sites on surface of K+-ISM.•The performance of the as-prepared K+-ISFET was improved.