Amplification of arsenic sensitivity in functionalized zinc oxide field effect transistor through optimization of gate electrostatics

Abstract

Demand for the detection of poisonous arsenic ions in water is increasing due to uncontrolled industrial and human activities. Conventional detection methods are found to be very complex, cumbersome, and non-portable. This paper presents curcumin functionalized zinc oxide field effect transistor for selective detection of arsenic ions in water, with high sensitivity and stability. The operating voltage of the device is optimized to 2.9 V through output characteristics, which ensures low power consumption. The presence of curcumin on ZnO surface imparts high degree of selectivity toward arsenic ions, and ZnO nanorods ensures high surface to volume ratio for adsorption. The device is tested against eight metal ions commonly found in water and is found to be highly selective toward arsenic. The device exhibits a sensitivity of 102 nA/ppb at zero gate voltage, which is further amplified to 366 nA/ppb by applying 2.4 V gate bias. The application of gate bias plays a pivotal role for enhancing the device sensitivity by 266% for 5 ppb arsenic concentration. The sensor shows a response time of 67 s and is found to be highly stable against adverse conditions. The sensor shows high resilience in the degradation of sensing performance for a duration of 40 days. Therefore, curcumin functionalized zinc oxide field effect transistor with proper gate bias shows promising results to be used as a portable, low-cost, and user-friendly arsenic ion detector system in future.