As wearable devices and medical implants become more common, their likelihood of being targeted by hackers increases, with stakes that could be even higher than traditional computer viruses. But researchers at Purdue University have developed a way to improve both the security and longevity of these devices: a switch from conventional electromagnetic wireless signals to lower-frequency electro-quasistatic signals.

The premise of the research is that people are increasingly becoming “body area networks” for wrist, head, and internal devices that can either be controlled solely by the user or externally — the latter for better or worse. Someone with a Bluetooth-capable defibrillator might want to provide near-field wireless access for a doctor’s checkup or ongoing battery monitoring, but not be susceptible to getting shocked or disabled by a hacker sitting 10 or 30 feet away.

Today, most wearables and implants communicate using radio signals: Bluetooth transmitters operate in the 2.4GHz range, and can be picked up within at least 33-foot radiuses. Relying instead on low-frequency electro-quasistatic signals, the Purdue researchers can limit the broadcasting range to a centimeter beyond the user’s skin, enabling the wearer or a doctor to interact with the device while keeping hackers at bay.

Electro-quasistatic signaling is also more efficient than other alternatives. The researchers say that it uses 100 times less power compared with Bluetooth, which means smaller batteries and thus smaller devices. Purdue Professor Shreyas Sen is working to create a “dust-sized” IC for the device, which in a prototype watch form is able to send signals anywhere on the body.

Potential applications go well beyond today’s wearables and implantables. Sen’s team expects that next-generation implantable machines could be reprogrammed so specifically as to “function as drugs… without the side effects,” and without the need for further post-installation surgeries.

Purdue’s full research paper, “Enabling Covert Body Area Network using Electro-Quasistatic Human Body Communication,” is available here. The technology has been patented, and the team is working toward commercializing it.