Ion Sensitive Transparent-Gate Transistor for Visible Cell Sensing

Abstract

In this study, we developed an ion-sensitive transparent-gate transistor (IS-TGT) for visible cell sensing. The gate sensing surface of the IS-TGT is transparent in a solution because a transparent amorphous oxide semiconductor composed of amorphous In-Ga-Zn-oxide (a-IGZO) with a thin SiO film gate that includes an indium tin oxide (ITO) film as the source and drain electrodes is utilized. The pH response of the IS-TGT was found to be about 56 mV/pH, indicating approximately Nernstian response. Moreover, the potential signals of the IS-TGT for sodium and potassium ions, which are usually included in biological environments, were evaluated. The optical and electrical properties of the IS-TGT enable cell functions to be monitored simultaneously with microscopic observation and electrical measurement. A platform based on the IS-TGT can be used as a simple and cost-effective plate-cell-sensing system based on thin-film fabrication technology in the research field of life science.

Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge

“…46 In summary, the experimental data are highly variable due to variation between silica surface preparation and electrolyte composition; however, molecular dynamics simulations and mean-field models show a qualitative agreement with some experimental data up to highly effective pH. 46 Silica often shows a sub-Nernstian response 114 in the 30-40 mV per pH range, 8,46,112,114 but the ideal Nernst response (∼59 mV per pH) has been reported 89 as shown in Fig. 6 ( pink circles).…”

“…If sputtered silica demonstrates a higher nanoscale surface area, the results of the present work provide a potential theoretical explanation for why sputtered silica has evidenced enhanced pH response compared to thermally grown silica. 89 As presented in the background, some experiments support the concept of nano-texturing resulting in increased pH response, [89][90][91][92] but the relationship remains unclear with further work being required to clarify the precise relationship.…”

“…When comparing two systems with identical hydroxyl densities and compositions, commonly-used site-binding models predict no effect on sensor response from changes in surface morphology. Nonetheless, some experiments suggest that amorphous surfaces are beneficial to pH sensor response: for example, sputtered silica was shown to have a higher pH sensitivity than thermally grown silica, 89 the addition of nanowires to a planar Al 2 O 3 /SiO 2 surface increased pH sensitivity by 5 mV per pH (55 mV per pH to 60 mV per pH), 90 and texturing a silanised silica surface with silanised silica nanoparticles increased pH sensitivity by 11 mV per pH (43 mV per pH to 54 mV per pH). 91,92 However, other experiments have shown no effect of increased surface porosity on pH sensitivity, but it did show an increase in capacitance.…”

“…The literature data are displayed with the electrolyte used in the legend, and were measured by using methods indicated by markers: ◆ X-Ray Photoelecton Spectroscopy (XPS), 109 ■ Electrolyte-on-insulator (EOS), 88 , ★ Impedance 110 • IS-FET. 89,[111][112][113] Experimental data are plotted as a function of measured pH, whereas simulated data are plotted as a function of surface charge density, with both the axes aligned using the approximate linear empirical relationship between surface charge density and pH described in the Methods section. The high pH sensitivity of the data of Sakata et al was obtained using a sputtered silica sample, as opposed to conventional thermally grown or native oxide, and for these data, the point-of-zero charge was not identified, so only potential differences can be shown, with the data manually aligned to a point-of-zero charge of ∼3 in agreement with typical experiments.…”

Electropolymerized Poly(toluidine blue O) Film Electrode for Potentiometric Biosensing

“…Additionally, the spikelike structure is considered to have contributed to the improved pH responsivity and sensitivity. Basically, the pH response of the oxide gate surface should be Nernstian when potentiometric sensors are used; (28,29) the Nernstian response is calculated to be 59.1 mV/pH at 25 ℃ using…”