This paper demonstrates a micropower offset- and temperature-compensated smart pH sensor, intended for use in battery-powered RFID systems that monitor the quality of perishable products. Low operation power is essential in such systems to enable autonomous logging of environmental parameters, such as the pH level, over extended periods of time using only a small, low-cost battery. The pH-sensing element in this work is an ion-sensitive extended-gate field-effect transistor (EGFET), which is incorporated in a low-power sensor front-end. The front-end outputs a pH-dependent voltage, which is then digitized by means of a co-integrated incremental delta-sigma ADC. To compensate for the offset and temperature cross-sensitivity of the EGFET, a compensation scheme using a calibration process and a temperature sensor has been devised. A prototype chip has been realized in a 0.16 μ m CMOS process. It occupies 0.35 × 3.9 mm 2 of die area and draws only 4 μ A from a 1.8 V supply. Two different types of custom packaging have been used for measurement purposes. The pH sensor achieves a linearity of better than ±0.1 for pH values ranging from 4 to 10. The calibration and compensation scheme reduces errors due to temperature cross-sensitivity to less than ±0.1 in the temperature range of 6°C to 25°C.

Saleh Heidary Shalmany

Matthias Merz

Ali Fekri

Zu-yao Chang

Romano J. O. M. Hoofman

Michiel A. P. Pertijs

Journal of Sensors

JOURNAL OF SENSORS 发表与传感器各个方面相关的论文，从其理论和设计，到完整传感设备的应用。涵盖所有类别的传感器，包括声学、生物、化学、电子、电磁（包括光学）、机械、接近和热传感器。鼓励与可穿戴、可植入和遥感设备相关的提交。设想的应用包括但不限于： -医疗、保健和生活方式监测 -环境和大气监测 -工程、制造和加工行业的传感 -运输、导航和地理定位 - 机器人和无人机的视觉、感知和传感该杂志欢迎文章，以及传感器技术本身，考虑现代传感器实施的实际方面，如网络、通信、信号处理和数据管理。除了原创研究外，《传感器杂志》还发表重点评论文章，检查最先进的技术，识别新兴趋势，并为发展领域提出未来方向。

The Journal of Sensors publishes papers related to all aspects of sensors, covering everything from theory and design to the application of complete sensing devices. It encompasses all categories of sensors, including acoustic, biological, chemical, electronic, electromagnetic (including optical), mechanical, proximity, and thermal sensors. Submissions related to wearable, implantable, and remote sensing devices are encouraged. Potential application areas include but are not limited to: medical, health, and lifestyle monitoring; environmental and atmospheric monitoring; sensing in engineering, manufacturing, and processing industries; transportation, navigation, and geolocation; as well as vision, perception, and sensing in robotics and drones. The journal welcomes articles on sensor technology itself, considering practical aspects of modern sensor implementation such as networking, communication, signal processing, and data management. In addition to original research, the Journal of Sensors also publishes focused review articles that examine cutting-edge technologies, identify emerging trends, and propose future directions for the development of the field.

《Journal of Sensors》发表与传感器相关的各个方面的论文，涵盖从理论和设计到完整传感设备的应用。涉及所有类型的传感器，包括声学、生物、化学、电子、电磁（包括光学）、机械、接近和热传感器。我们鼓励与可穿戴、可植入和遥感设备相关的投稿。设想的应用领域包括但不限于：医疗、健康和生活方式监测；环境和大气监测；工程、制造和加工行业的传感；运输、导航和地理定位；以及机器人和无人机的视觉、感知和传感。该杂志欢迎关于传感器技术的文章，特别关注现代传感器实施的实际方面，如网络、通信、信号处理和数据管理。除了原创研究外，《Journal of Sensors》还发表重点评论文章，审视最先进的技术，识别新兴趋势，并为该领域的发展提供未来方向。

A 7 <i>μ</i>W Offset- and Temperature-Compensated pH-to-Digital Converter

A micropower offset- and temperature-compensated smart pH sensor, intended for use in battery-powered RFID systems that monitor the quality of perishable products and reduces errors due to temperature cross-sensitivity to less than ±0.1.

Category	Quartile
工程技术	4
工程技术, 工程电子与电气	4
工程技术, 仪器仪表	4

A 7 μW Offset- and Temperature-Compensated pH-to-Digital Converter

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Journal Info

Category	Quartile
INSTRUMENTS & INSTRUMENTATION	3