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New Technique for Wearable Sensors Transmits Signal Through Body

Xconomy San Diego — 

Electrical engineers at UC San Diego have reported a new wireless communication technique that uses magnetic fields to transmit ultra low-power signals through the human body.

At a time when forecasts of the global market for wearable wireless technologies range from $6 billion to $19 billion by 2018, a UC San Diego spokeswoman said the team already has filed for patent protection—staking an early claim for potential commercial applications. One obvious application would be a wireless sensor network for full-body health monitoring.

Today most smart watches, eyeglasses, apparel, and other wearable sensors use wireless Bluetooth technology to communicate directly with each other, and connect to the Internet through a smartphone or similar mobile device. The underlying problem is that Bluetooth radios require a lot of power to operate, and the battery life for most Internet-connected devices is relatively short.

At UC San Diego, a team led by Patrick Mercier of the Center for Wearable Sensors sought to take advantage of the fact that magnetic field communications through the human body is far more efficient than using Bluetooth radios. The San Diego researchers say magnetic fields are able to pass freely through biological tissue—and require far less power in the process.

Bluetooth radio signals, however, do not easily pass through the human body. They typically require a power boost to help overcome the signal degradation known as “path loss.”

So the team developed an ultra-low-power prototype that uses the body itself as the medium for communications between wearable gadgets. In a proof-of-concept demonstration by Jiwoong Park, a doctoral student in electrical engineering, the team successfully transmitted signals from one arm to the other, using “magnetic field human body communications.”

The team did not measure how much power the technique used. The UC San Diego researchers did show, however, that the path losses associated with Bluetooth radios are close to 10 million times higher than losses with magnetic field human body communication.

The engineers presented their findings last week at the 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society in Milan, Italy.

magnetic field human body communications

Jiwoong Park, an electrical engineering Ph.D. student at UC San Diego, demonstrates magnetic field human body communications.