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<p>This work presents a comprehensive simulation- and analytical-based study of the hydrogen-ion sensitivity of electrolyte solutions over a pH range of 1–10. A novel AlGaN/GaN high-electron-mobility transistor (HEMT) sensor with an embedded cavity at the drain side is proposed, in which the electrolyte interacts with an SiO<sub>2</sub> sensing membrane. To enhance surface reactivity and improve sensitivity, the membrane is functionalized with 3-aminopropyltriethoxysilane (APTES), which provides additional active binding sites for proton exchange. The influence of varying pH levels within the nanocavity is examined by corresponding changes in the threshold voltage and shifts in the drain current. By optimizing the gate voltage at the point of maximum transconductance, the device achieves greater responsiveness to changes in ionic pH. The proposed sensor demonstrates an impressive average threshold voltage sensitivity of 183.58&#xa0;mV/pH, which is significantly higher than the Nernstian limit of 59&#xa0;mV/pH, while achieving a current sensitivity of 27.5&#xa0;mA/mm/pH. Further, the device’s sensing performance is assessed under varying environmental temperature conditions, demonstrating its operational stability. These findings underscore the device’s substantial potential for high-performance pH-sensing applications.</p>

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Ultra-Sensitivity AlGaN/GaN HEMT Sensor with Embedded Cavity for pH Detection Beyond the Nernstian Limit

  • 期刊论文

  • 发表日期：

    2026年5月27日

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  • Samarendra Samal,
  • Ashish Kumar,
  • Guru Prasad Mishra

摘要

This work presents a comprehensive simulation- and analytical-based study of the hydrogen-ion sensitivity of electrolyte solutions over a pH range of 1–10. A novel AlGaN/GaN high-electron-mobility transistor (HEMT) sensor with an embedded cavity at the drain side is proposed, in which the electrolyte interacts with an SiO2 sensing membrane. To enhance surface reactivity and improve sensitivity, the membrane is functionalized with 3-aminopropyltriethoxysilane (APTES), which provides additional active binding sites for proton exchange. The influence of varying pH levels within the nanocavity is examined by corresponding changes in the threshold voltage and shifts in the drain current. By optimizing the gate voltage at the point of maximum transconductance, the device achieves greater responsiveness to changes in ionic pH. The proposed sensor demonstrates an impressive average threshold voltage sensitivity of 183.58 mV/pH, which is significantly higher than the Nernstian limit of 59 mV/pH, while achieving a current sensitivity of 27.5 mA/mm/pH. Further, the device’s sensing performance is assessed under varying environmental temperature conditions, demonstrating its operational stability. These findings underscore the device’s substantial potential for high-performance pH-sensing applications.