# Study of a Palladium (Pd)/Aluminum-Doped Zinc Oxide (AZO) Hydrogen Sensor and the Kalman Algorithm for Internet-of-Things (IoT) Application

Wei Cheng Chen, Jing Shiuan Niu, I. Ping Liu, Cheng Yu Chi, Shiou Ying Cheng, Kun Wei Lin, Wen Chau Liu

Research output: Contribution to journalArticlepeer-review

## Abstract

A palladium (Pd) thin film is decorated on a radio frequency (RF) sputtered aluminum-doped zinc oxide (AZO) thin film to produce a hydrogen sensor. Due to the catalytic activity of the Pd metal, the studied thin film-based device shows remarkably enhanced hydrogen-sensing characteristics. Experimentally, a very high sensing response of $1.12\times 10 ^{4}$ with a response time of 23 s is obtained under 1% H2/air gas at 300 °C. Furthermore, even under an extremely low concentration of 40-ppb H2/air, a sensing response of 0.17 is acquired. The optimal operating temperature of the studied device is 300 °C. A hypothesis is used to interpret the related hydrogen-sensing mechanism of the studied device. A thermodynamic analysis is employed to study the surface coverage of hydrogen molecules on the device's surface. Furthermore, for the application in wireless transmission of the Internet of Things (IoT), an interesting Kalman algorithm is used to reduce redundant data, save hardware costs, and reduce network congestion. The simulated results show that 93.9% of the redundant data can be removed. The studied device exhibits advantages of a simple structure, easy fabrication, low cost, a widespread sensing range of hydrogen concentration, a very high sensing response, and an extremely low detecting limit, as well as being suitable for IoT application.

Original language English 9186844 4405-4412 8 IEEE Transactions on Electron Devices 67 10 https://doi.org/10.1109/TED.2020.3018084 Published - 2020 Oct

## All Science Journal Classification (ASJC) codes

• Electronic, Optical and Magnetic Materials
• Electrical and Electronic Engineering