The Hunt for Power Remote Sensing

With the advent of the Internet of Things (IoT), the need for ultra-low power passive remote sensing is on the rise for battery-powered technologies. Always-on motion-sensing technologies are a great option to turn to. Digital cameras have come light years from where they were a decade ago, but low power they are not. When low-power technologies need always-on remote sensing, infrared motion sensors are a great option to turn to.

Passive infrared (PIR) sensors and passive infrared detectors (PIDs) are electronic devices that detect infrared light emitted from objects within their field of view. These devices typically don’t measure light per se; rather, they measure the delta of a system’s latent energy. This change generates a very small potential across a crystalline material (gallium nitride, cesium nitrate, among others), which can be amplified to create a usable signal.

Infrared technology was built on a foundation of older motion-sensing technologies that came before. Motion sensing was first utilized in the early 1940s, primarily for military purposes nearing the end of World War II. Radar and ultrasonic detectors were the progenitors of motion-sensing technologies seen today, relying on reflecting sound waves to determine the location of objects in a detection environment. Though effective for its purpose, its use was limited to military applications and was not a reasonable option for commercial users.

This essay appears in Circuit Cellar 314 (September 2016).

The viability of motion detection tools began to change as infrared-sensing options entered development. The birth of modern PIR sensors began towards the end of the sixties, when companies began to seek alternatives to the already available motion technologies that were fast becoming outdated.

The modern versions of these infrared motion sensors have taken root in many industries due to the affordability and flexibility of their use. The future of motion sensors is PID, and it has several advantages over its counterparts:

  • Saving Energy—PIDs are energy efficient. The electricity required to operate PIDs is minimal, with most units actually reducing the user’s energy consumption when compared to other commercial motion-sensing devices.
  • Inexpensive—Cost isn’t a barrier to entry for those wanting to deploy IR motion sensing technology. This sensor technology makes each individual unit affordable, allowing users to deploy multiple sensors for maximum coverage without breaking the bank.
  • Durability—It’s hard to match the ruggedness of PIDs. Most units don’t employ delicate circuitry that is easily jarred or disrupted; PIDs are routinely used outdoors and in adverse environments that would potentially damage other styles of detectors.
  • Simple and Small—The small size of PIDs work to their advantage. Innocuous sensors are ideal for security solutions that aren’t obtrusive or easily noticeable. This simplicity makes PIDs desirable for commercial security, when businesses want to avoid installing obvious security infrastructure throughout their buildings.
  • Wide Lens Range—The wide field of vision that PIDs have allow for comprehensive coverage of each location in which they are placed. PIDs easily form a “grid” of infrared detection that is ideal for detecting people, animals, or any other type of disruption that falls within the lens range.
  • Easy to Interface With—PIDs are flexible. The compact and simple nature of PIDs lets the easily integrate with other technologies, including public motion detectors for businesses and appliances like remote controls.

With the wealth of advantages PIDs have over other forms of motion-sensing technology, it stands to reason that PIR sensors and PIDs will have a place in the future of motion sensor development. Though other options are available, PIDs operate with simplicity, energy-efficiency, and a level of durability that other technologies can’t match. Though there are some exciting new developments in the field of motion-sensing technology, including peripherals for virtual reality and 3-D motion control, the reliability of infrared motion technology will have a definite role in the evolution of motion sensing technology in the years to come.

As the Head Hardware Engineer at Cyndr (, Kyle Engstrom is the company’s lead electron wrangler and firmware designer. He specializes in analog electronics and power systems. Kyle has bachelor’s degrees in electrical engineering and geology. His life as a rock hound lasted all of six months before he found his true calling in engineering. Kyle has worked three years in the aerospace industry designing cutting-edge avionics.