Nanotech hearing aids due out next month will carry spintronic sensors that automatically adjust to accommodate the source of sounds. If a phone is held to the wearer's ear, for example, the hearing aid will automatically switch modes without the person's intervention. Giant magnetoresistance (GMR) sensors from NVE Corp. (Eden Prairie, Minn.) are at the heart of the hearing aids, built by Starkey Laboratories (Minneapolis). The sensors are based on a chip that uses electron spin rather than charge to store information. By automatically switching modes, the sensor frees a wearer from today's need to switch either manually or with a bulky switch. The sensor, one-third the size of the switch's coil, is built from nanoscale layers of magnetic thin films just a few atomic layers thick. The result, say both companies, is a magnetic sensor that's smaller, more precise and less power-hungry than devices available today. "Our hearing aids can now be built much smaller and perform significantly better," said Dale Lizakowski, a quality engineer at Starkey Labs. "I have personally worn and tested the GMR sensor, and it performs well above and beyond any other technology for switching sensitivity, overall reliability and ultrasmall size."