High-precision silicon nanowire array sensor for quantitating ambient humidity and pH value

Abstract This paper presents a high sensitivity silicon nanowire (SiNW) array sensor for precisely quantitating humidity and pH value. Well-aligned nanowires with ordered separation have been fabricated via low-cost and highly controllable traditional top-down fabrication techniques, which are fully compatible with complementary metal oxide semiconductor (CMOS) technology. Compared to bottom-up fabrication techniques, better reproducibility and stability in these procedures are indicated by fabrication results. The packaged SiNW array devices exhibit excellent linearity and repeatability when tested for humidity. Alternatively, the SiNW arrays give a quick and accurate reflection to hydrogen ion concentration after functionalized with APTES solution. Notably, the accuracy of the sensor can reach 0.1 pH. To characterize the immunity and long-term stability of the sensor, the performance of the SiNW array sensor at different temperatures and times was investigated in detail. The test results show that the SiNW array sensor has excellent test performance in gas and liquid environments, and the design makes it more competitive than those of commercialized sensors.