Internet of Things and Data Analytics Handbook

10ELECTRO‐OPTICAL INFRARED SENSOR TECHNOLOGIES FOR THE INTERNET OF THINGS

VENKATARAMAN SUNDARESWARAN, HENRY YUAN, KAI SONG, JOSEPH KIMCHI AND JIH‐FEN LEI

Teledyne Judson Technologies, Montgomeryville, PA, USA

10.1 INTRODUCTION

Sensors at the network edge are essential to most Internet of Things (IoT) devices. While there are a number of ways of sensing the environment using electromechanical, electrochemical, and chemical sensors, optical sensing plays a dominant role due to its versatility and accuracy. A large variety of interesting phenomena can be sensed with optical sensors. Some examples are temperature, gas, food quality, chemical species, humidity, moisture, liquid level, position, distance, displacement, velocity, acceleration, laser power, pressure, strain, and flow. Electro‐Optical (EO) sensing denotes the process by which optical indicators are converted to electrical signals.

Simple EO devices are found everywhere in the form of photodiodes that sense a break in a beam of infrared (IR) light—as used in elevator and garage doors to prevent closing on a person or in a water faucet to sense the presence of a hand. Noncontact temperature monitoring, or Remote Thermal Sensing, is dominated by EO devices in industrial process control applications such as in steel, aluminum, glass, cement, plastic, and semiconductor processing. EO sensors provide the temperature feedback to control these processes. The EO sensors operate in the IR wavelength applicable to the process ...