Electrolyte-gated SrCoOx FET sensor for highly sensitive detecting pH in extreme alkalinity solution

Fe-Doped SrCoOx FET Sensors for Extreme Alkaline pH Sensing

“…In Figure a, the temporal resistance change of the Fe-doped SrCoO x pH sensor over time as the NaOH concentration varies from 1 to 10 mol/L is depicted, along with the influence of an external electric field on the rate of resistance change. It can be observed that when the doping level is 5 mol % and the bias voltage is 0 V, the response time of the sensor is comparable to that of the undoped SrCoO x pH sensor . The response takes approximately 3500 s to complete, during which the resistance changes from about 1.4 MΩ at 1 mol/L NaOH concentration to around 20 kΩ at 10 mol/L NaOH concentration When the doping level is increased to 10 mol %, the response time reduces to approximately 1200 s, with the resistance changing from about 15 kΩ at a 1 mol/L NaOH concentration to approximately 2.5 kΩ at a 10 mol/L NaOH concentration.…”

“…It can be observed that when the doping level is 5 mol % and the bias voltage is 0 V, the response time of the sensor is comparable to that of the undoped SrCoO x pH sensor. 22 The response takes approximately 3500 s to complete, during which the resistance changes from about 1.4 MΩ at 1 mol/L NaOH concentration to around 20 kΩ at 10 mol/L NaOH concentration When the doping level is increased to 10 mol %, the response time reduces to approximately 1200 s, with the resistance changing from about 15 kΩ at a 1 mol/L NaOH concentration to approximately 2.5 kΩ at a 10 mol/L NaOH concentration. This reduction in response time is attributed to the presence of tetragonal and orthorhombic brownmillerite phases in SrCo 0.95 Sc 0.05 O x at low Fe doping levels, which affect the migration and diffusion of oxygen ions.…”

“…Among perovskite materials, the SrCoO x -based electrolyte-gated FET sensors exhibit stable measurements and a high level of sensitivity to pH levels in highly alkaline environments . In contrast to conventional FET pH sensors which are based on the electrical double layer, SrCoO x -based electrolyte-gated FET sensors could effectively detect extreme alkalinity through the introduction of O 2– into the oxygen vacancies (V o ) of SrCoO x by the presence of concentrated OH – . − The reduction of V o leads to a transition in the semiconductor-metallicity characteristics of SrCoO x , resulting in an unparalleled sensing capability toward extreme alkaline conditions .…”