Robust Carbon Nanotube Transistor Ion Sensors with Near-Nernstian Sensitivity for Multi-Ion Detection in Neurological Diseases.

Accurate monitoring of sodium and potassium ions in biological fluids is crucial for diseases related to electrolyte imbalance. Low-dimensional materials such as carbon nanotubes can be used to construct biochemical sensors based on high-performance field effect transistor (FET), but they face the problems of poor device consistency and difficulty in stable and reliable operation. In this work, we mass-produced carbon nanotube (CNT) floating-gate field-effect transistor devices with high uniformity and consistency through micro-/nanofabrication technology to improve the accuracy and reliability of detection without the need for statistical analysis based on machine learning. By introducing waterproof hafnium oxide gate dielectrics on the CNT FET channel, we not only effectively protect the channel area but also significantly improve the stability of the sensor. We have prepared array sensing technology based on CNT FET that can detect potassium, sodium, calcium, and hydrogen ions in artificial cerebrospinal fluid. The detection concentration range is 10 μM-100 mM and pH 3-pH 9, with a sensitivity close to the Nernst limit, and exhibits selective and long-term stable responses. This could help achieve early diagnosis and real-time monitoring of central nervous system diseases, highlighting the potential of this ion-sensing platform for highly sensitive and stable detection of various neurobiological markers.