Study on Extended Gate Field Effect Transistor with Nano-TiO-2 Sensing Membrane by Sol-Gel Method

The nano-titanium dioxide (nano-TiO_2) sensing membrane,fabricated by sol-gel technology,was used as the pH-sensing layer of the extended gate field effect transistor (EGFET) device.The objective of this research is the preparation of titanium dioxide materials by sol-gel method using Ti(OBu)_4 as the precursor.In this study,we fabricated a nano-titanium dioxide sensing layer on the ITO glass by dip coating.In order to examine the sensitivity of the nano-TiO_2 films applied to the EGFET devices,we adopted the ITO glass as substrate,and measured theⅠ_(DS)-Ⅴ_G curves of the nano-titanium dioxide separative structure EGFET device in the pH buffer solutions that have different pH values by the Keithley 236 Instrument.By the experimental results,we can obtain the pH sensitivities of the EGFET with nano-TiO_2 sensing membrane prepared by sol-gel method,which is 59.86mV/pH from pH 1 to pH 9.

Preparation and Properties of Sensing Membrane for Fiber Optic Oxygen Sensor

Four sensing membranes based on fluorescence quenching were prepared by sol-gel method and CA membrane method, and the Ru(Ⅱ) complexes, Ru( bpy)3 Cl2 and Ru(phen)3 Cl2 , were used as the indicators . The results indicate that the volume fraction of oxygen o2 have a linear relationship in large scale with tan0/tanfor all of the sensing membranes. They have super properties such as excellent limit of detection ,fast response time and good reproducibility. The stability of the sensing membranes made by sol-gel method is better than those by CA membranes, but the uniformity of the latter is better than that of the former.

Preparation and Properties of Modified Sol-Gel Sensing Membrane for Fiber Optic Oxygen Sensor

Modified sensing membranes based on fluorescence quenching were prepared by the sol-gel method,using formamide as the drying control chemical additive,tetraethoxysilane as the main material,Ru(phen) 3Cl 2 as the indicator.The membrane with the optimum thickness of 20-50μm is uniform and crack-free,in which the indicator has a very small leaking rate.The membrane is immersed in water for 50h,the membrane sensing parameter M decreases by less than 5%.The fiber optic oxygen sensor with the sensing membrane has a detection limit of 5×10 -6M(ppm),a response time of less than 30s,excellent reproducibility and stability.

Fiber-optic dual Fabry-Pérot interferometric carbon monoxide sensor with polyaniline/Co3O4/graphene oxide sensing membrane

An optical fiber dual Fabry-Perot interferometric carbon monoxide gas sensor based on PANI/Co3 O4/GO(PCG)sensing membrane coated on the end face of the optical fiber is proposed and fabricated.One end face of photonic crystal fiber(PCF)without cut-off wavelength is fused with a single-mode fiber(SMF),and the other end face of the PCF is coated with PCG sensing membrane.The collapsed layer formed during the air hole fusion of PCF is used as the first reflector,the interface between PCF and sensing membrane is used as the second reflector,and the interface between the sensing membrane and the air is used as the third reflector,thus the dual Fabry-Pe rot structure sensor is formed.The results show that the sensor has excellent sensitivity and selectivity to carbon monoxide.With the increasing concentration of carbon monoxide gas in the range of 0-60 ppm,the intensity of interference spectrum decreases.The sensitivity of the sensor is 0.3473 dB m/ppm,and its linearity is good.The response time and recovery time are 68 s and 106 s,respectively.The sensor has the advantages of the compact size,low cost,high sensitivity,strong selectivity and simple structure.It is suitable for the sensing detection of low concentration carbon monoxide gas.

Study on the Tin Oxide Sol-Gel Membrane as a pH Sensing Electrode

In this study,tin oxide sensing membrane was derived by sol-gel method and was coated onto indium tin oxide (ITO) glass substrate by spin-coating technique to fabricate a pH sensing electrode.Besides,the morphology of the tin oxide membrane has been discussed through the instrumental analysis.Furthermore,the sensing characteristics of the pH electrode was measured by commercial instrumental amplifier as the readout circuit.Owing to the sol-gel method has many advantages such as easy fabrication of gel solution,ability to dope other materials without any expensive fabricating equipment.Hence,it is suitable for the mass production of a disposable sensor.