Implantable Health Tech devices such as defibrillators and pacemakers can be life savers, but come with their own technical issues. If we’re going to be implanting medical devices to regulate, control, assist, measure, and monitor vital body functions, fast and accurate communications with the devices can mean the difference between life and death. Unfortunately, current radio frequency (RF) wireless communications technologies for implants are limited by two major factors.
The FCC parcels out available frequency bands in the radio spectrum and the frequency can dictate speed. The frequency granted to implantable devices is limited to 50 kbps. If the only signal content is “I’m working” then perhaps that speed is sufficient, but if real-time imagery is required, performance degrades rapidly. The second issue with RF (radio frequency) wireless is signal degradation. Signals are slowed by salt water (which is more than 70% of our bodies) and also are impeded by solid or mushy objects (say like bones and organs). So you get the picture: a low payload at a slow speed being knocked down further. Enter engineers who work in long-distance sonar.
It occurred to engineers at the University of Illinois Urbana-Champaign, that the human body is quite like the ocean. We’re bags of salt water with some solid matter and floating bits of tissue. From their work with long distance oceanic ultrasound, although generally at speeds under 100 kbps, they knew there was no signal degradation. Short distance tests had worked up to 120 mbps. So they set up a test bed sending ultrasonic transmissions from a tank of salt water through meat. They tested with pork loin and with beef liver. The test results have significant implications for use with implanted biomedical devices. With both types of meat, the researchers were able to sustain speeds of 20-30 Mbps, which is fast enough to stream HD video. And it’s 400 times faster than current RF transmission rates. Finally, ultrasound is already widely used in medical applications, and may have less negative impact on body tissues than RF emissions.
The next steps will be to test on living tissue and then eventually on humans. However, it may not be too far in the future when you can read updates from your liver, your lower intestine, and your brain on your smartphone using sound waves.