Extended-Gate FET Biosensor Based on GaN Micropillar Array and Polycrystalline Layer: Application to Hg<sup>2+</sup> Detection in Human Urine
Jialing Zhou, Hui Huang, Hui Huang, Qian Wang, Zhirui Li, Shunji Chen, Jun Yu, Yuan Zhong, Jing Chen, Huolin Huang, Huolin Huang
Abstract
Owing to the separation of field-effect transistor (FET) devices from sensing environments, extended-gate FET (EGFET) biosensor features high stability and low cost. Herein, a highly sensitive EGFET biosensor based on a GaN micropillar array and polycrystalline layer (GMP) was fabricated, which was prepared by using simple one-step low-temperature MOCVD growth. In order to improve the sensitivity and detection limit of EGFET biosensor, the surface area and the electrical conductivity of extended-gate electrode can be increased by the micropillar array and the polycrystalline layer, respectively. The designed GMP-EGFET biosensor was modified with l -cysteine and applied for Hg 2+ detection with a low limit of detection (LOD) of 1 ng/L, a high sensitivity of −16.3 mV/lg(μg/L) and a wide linear range (1 ng/L-24.5 μg/L). In addition, the detection of Hg 2+ in human urine was realized with an LOD of 10 ng/L, which was more than 30 times lower than that of reported sensors. To our knowledge, it is the first time that GMP was used as extended-gate of EGFET biosensor.