Airplane manufacturers running noise tests on new aircraft now have a much cheaper option than traditional wired microphone arrays. And it’s sensitive enough to help farmers with pest problems. The wireless microphone array that one company recently created with help from NASA can locate crop-threatening insects by listening for sounds they make in fields. And now, it’s making fast, affordable testing possible almost anywhere.

Since releasing its first commercial product in 2017, a sensor for wind tunnel testing developed with extensive help from NASA, UF startup Interdisciplinary Consulting Corporation (IC2) has doubled its staff size and moved to larger lab and office space to produce its new WirelessArray product. The Gainesville company started in 2014 licensing technology developed by Dr. Mark Sheplak from UF’s Department of Electrical and Computer Engineering.

Interested in making its own flight tests more affordable, NASA’s Langley Research Center in Hampton, Virginia, supported IC2’s new project as well, with multiple Small Business Innovation Research (SBIR) contracts and expert consulting.

The result is a series of small, saucer-shaped bases equipped with multiple sensors that measure the air pressure changes created by overhead sounds. Airplanes go through noise testing and require certification, so they don’t exceed the FAA noise level set for the body type. When an airplane flies directly overhead, the array collects noise data to build a two-dimensional map of the sound pressure and its source. A custom software package translates that information for the end user.

Most sensors and electronic devices are designed to perform up to a temperature of 125ºC. In a variety of situations (think hypersonic air vehicles, inside combustion chambers, on the surface of other planets), it would be helpful to be able to measure the fluctuating pressure on a particular surface in an extreme environment. Currently, no sensors can take the heat. The HOTS program challenged researchers to create devices not only capable of withstanding such temperatures but also delivering reliable operations up to a million times every second, thus requiring a sensor bandwidth of 1MHz.

From the DARPA program description:

“…the capabilities of sensors can be inhibited by thermal limitations. A sensor may theoretically be able to process inputs such as speed, pressure, or the integrity of a mechanical component, but inside a turbine engine, temperatures far exceed what any existing sensor can withstand. However, if we can design, integrate, and demonstrate high-performance physical sensors that can operate in high-temperature environments, we can advance toward systems that perform at the edge of their capability instead of the limits of uncertainty.”

Technical problems in extreme-temperature pressure sensing have persisted since at least as early as the beginning of hypersonics research in late 1946. Then the term was coined by Cal Tech aerodynamicist Hsue-Shen Tsien. When Sheplak began his dissertation work in the early 1990s at NASA-Langley Research Center in instrumentation development for hypersonic turbulent boundary layer measurements, it was still an open problem. It’s only relatively recently — with advances in materials science, high-bandgap semiconductor circuit design, and MEMS technologies — that the fundamental problems can be tackled in earnest.