Chemically modified field-effect transistors; a sodium ion selective sensor based on calix[4]arene receptor molecules

Multifunctional Ion-Sensitive Floating Gate Fin Field-Effect Transistor with Three-Dimensional Nanoseaweed Structure by Glancing Angle Deposition Technology

A multifunctional ion-sensitive floating gate Fin field-effect transistor (ISFGFinFET) for hydrogen and sodium detection is demonstrated. The ISFGFinFET comprises a FGFET and a sensing film, both of which are used to detect and improve sensitivity. The sensitivity of the ISFGFinFET can be adjusted by modulating the coupling effect of the FG. A nanoseaweed structure is fabricated via glancing angle deposition (GLAD) technology to obtain a large sensing area to enhance the sensitivity for hydrogen ion detection. A sensitivity of 266 mV per pH can be obtained using a surface area of 3.28 mm² . In terms of sodium ion detection, a calix[4]arene sensing film to monitor sodium ions, obtaining a Na⁺ sensitivity of 432.7 mV per pNa, is used. In addition, the ISFGFinFET demonstrates the functionality of multiple ions detection simultaneously. The sensor arrays composed of 3 × 3 pixels are demonstrated, each of which comprise of an FGFET sensor and a transistor. Furthermore, 16 × 16 arrays with a decoder and other peripheral circuits are constructed and simulated. The performance of the proposed ISFGFinFET is competitive with that of other state-of-the-art ion sensors.

Potassium selective chemically modified field effect transistors based on AlGaN/GaN two-dimensional electron gas heterostructures

We investigate the use of the AlGaN/GaN high electron mobility transistor (HEMT) as a novel transducer for the development of ion-selective chemically modified HEMT sensors (ChemHEMTs). For this, polyvinyl chloride (PVC) membrane doped with ion-selective ionophores is deposited onto the area of the gate for the chemical recognition step, while the AlGaN/GaN HEMT is used as the transducer. In particular, the use of a valinocycin doped membrane with thickness of 50 microm generates a sensor with excellent analytical characteristics for the monitoring of K(+). The K(+)-ChemHEMT has sensitivity of 52.4 mV/pK(+)in the linear range of 10(-5) to 10(-2)M, while the detection limit is in the order of 3.1 x 10(-6)M. Also, the sensor shows selectivity similar to valinomycin-based ISEs, while the signal stability over time and the measurement to measurement reproducibility are very good.

An Au nanoparticle/bisbipyridinium cyclophane-functionalized ion-sensitive field-effect transistor for the sensing of adrenaline

A film consisting of polyethyleneimine (PEI), Au nanoparticles (12 +/- 1 nm) and coadsorbed cyclobis(paraquat-p-phenylene) (1) was assembled as a sensing interface on the Al2O3 insulating layer of an ion-sensitive field-effect transistor (ISFET). Adrenaline (2) was sensed by the functionalized ISFET with a detection limit of 1 x 10(-6) M. The sensing ability of the nanostructured device for the analysis of adrenaline originates from the preconcentration of the analyte in the cyclophane by pi-pi donor-acceptor interactions. Analysis of adrenaline is accomplished by the measurement of the source-drain current, Isd, or by the gate-source voltage, Vgs. The sensing device is reusable (at least 100 cycles) and exhibits high stability.