Field-effect transistor extended gate

The first dielectric material that was used on open gates of field effect transistors (ion-sensitive field effect transistor, ISFET) was silicon dioxide by Bergveld in 1970. The problem in the ISFET structure is the poor insulation between the device and the solutions. The ISFET structure was improved by using ion-sensitive electrodes (ISE). With field effect transistors the gate area can be extended by using a conductive wire covered with the sensitive membrane. This new approach helps in enhancing the stability, sensitivity, and flexibility in shaping i.e., miniaturization of pH-sensitive devices. 

T. Sakata, S. Matsumoto, Y. Nakajima, and Y. Miyahara, Potential behaviour of biochemically modified gold electrode for extended-gate field-effect transistor. Jpn. J. Appl. Phys. 44, 2860-2863 (2005). 

Extended-Gate Field-Effect Transistor (EGFET)... 

Batista, P.D., Mulato, M. ZnO extended-gate field-effect transistors as pH sensors, Appl. Phys. Lett. 87, 143508/1-3 (2005)... 

Guerra, E.M., Silva, G.R., Mulato, M. Extended gate field effect transistor using V2O5 xerogel sensing membrane by sol-gel method. Solid State Sci. 11, 456-460 (2009)... 

Chou, J.C., Kwan, P.K., Chen, Z.J. Sn02 Separative Structure Extended Gate H -Ion Sensitive Field Effect Transistor by the Sol-Gel Technology and the Readout Circuit Developed by Source Eollower. Jpn. J. Appl. Phys. 42, 6790-6794 (2003)... 

Chen, J.C., Chou, J.C., Sun, T.P., Hsiung, S.K. Portable urea biosensor based on the extended-gate field effect transistor. Sens. Actuat. B 91, 180-186 (2003)... 

Nguyen, T.N.T., Seol, Y.G., Lee, N.E. Organic field-effect transistor with extended indium tin oxide gate structure for selective pH sensing. Organic Electronics 12, 1815-1821 (2011)... 

T. Goda,Y. Miyahara, Detection ofmicroenvironmental changes induced by protein adsorption onto self-assembled monolayers using an extended gate-field effect transistor, Anal. Chem. 82 (2010) 1803-1810. 

Chen, C.-R, Ganguly, A., Lu, C.-Y. et al. (2011) Ultrasensitive in situ label-free DNA detection using a GaN nanowire-based extended-gate field-effect-transistor sensor. Anal. Chem., 83 (6), 1938-1943. 

Yun-Shan C, Wan-Lin T, Lee IC, Jung-Chuan C, Huang-Chung C (2012) A novel pH sensor of extended-gate field-effect transistors with laser-irradiated carbon-nanotube network. Electron Device Lett IEEE 33(11) 1622-1624. doi 10.1109/led.2012.2213794... 

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