Engineers from the University of California at Davis (UC Davis) have developed a new radar sensor that can detect movements as small as 100 human hairs. Even better, the sesame seed-sized sensor itself is energy efficient.

The system is based on millimeter wave radar technology, which, as the name suggests, are short-range radar sensors that operate at millimeter wave frequencies between microwaves and infrared. These sensors can accurately detect incredibly small movements of microscopic objects and potentially find applications in security, biometric tracking, and navigation for the blind. However, they have problems with power consumption and filtering background noise.

The UC Davis team’s device was designed to counter both of these issues. By adjusting the topology of the sensor, the team was able to tune it to remove unwanted noise from the measurements. This allows the sensor to detect changes in the object’s position that are only 100th the width of a human hair and to detect vibrations that are 1000th the width of a human hair.

Unlike other sensors with similar accuracy, this sensor is much smaller, approximately the size of a sesame seed. At the same time, its design increases energy efficiency and can be produced relatively easily.

The researchers say the sensor is designed to determine how thirsty a plant is by tracking subtle changes in leaf thickness (an indicator of hydration or dehydration). Having a set of these low-cost sensors could be vital for the agricultural industry. Other potential applications include monitoring the structural integrity of buildings or more accurate virtual reality systems, the team says.

The researchers plan to continue improving their design by allowing other scientists to experiment.