MIT's ReMix Wireless System Is An 'Innerspace' GPS For Inside Your Body

Engineers and researchers are constantly on the lookout for new ways to find problems inside the human body that allow doctors to determine what's going on internally without having to resort to cutting. A team from the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) led by Professor Dina Katabi is working on a new wireless system that the team likens to an in-body GPS system called ReMix. The system is designed specifically to locate ingestible implants inside the body using a low-power wireless signal from outside the body.

The idea is that the ReMix wireless system could allow medical personnel to determine the exact location of ingestible implants inside the body. Such tiny implants could be used to track tumors that shift around inside the body and to help monitor slight movements that might occur as the tumors are treated. So far, the system has been tested in animals and it has demonstrated the ability to track ingestible implants with a centimeter-level of accuracy. ReMix could eventually be used in a system that would allow these ingestible sensors to deliver drugs to specific regions of the body for treating diseases.

MIT scientists have tested ReMix in animals by implanting a small marker inside the animal tissue. A wireless device that reflects radio waves off the patient is then used to produce the signals to locate the implant. That same wireless radio signal device has been proven in the past to be able to detect heart rate, breathing, and movement. A special algorithm uses that radio signal to precisely locate the marker inside the body. Since the radio waves are transmitted from outside the body the internal marker doesn’t need to transmit any wireless signal on its own. That is important because it means the internal marker can be much smaller since it needs no battery or external source of energy. The internal marker simply reflects the radio signal produced outside the patient's body.

One big challenge for the ReMix team is that wireless signals from the device that reflect off the skin of the person are about 100 million times more powerful than the signals that the metal marker inside the body reflects. The team was able to overcome that issue by designing a system that separates interfering skin signals from signals that the team is trying to measure. That system uses a small diode able to mix the signals together so the team can filter out the skin-related signals.

MIT's team believes that one major application for ReMix is in proton therapy, which is a type of cancer treatment that bombards tumors with beams of magnet-controlled protons. That treatment allows doctors to prescribe very high doses of radiation treatment to fight tumors. For now, the system isn’t accurate enough for use in a clinical setting and work is ongoing on perfecting the system.