Five years ago a new technology came up, Red Tacton. It was intended to serve as HAN, Human Area Network, leveraging on our body electrical characteristics to transmit tiny electrical signals. A special transceiver would convert a signal generated by a device touching our body into a frequency that the human skin could carry and another device in touch with our body would be able to receive it.
Transmission occurred also as one body was in touch with another one, so that a cellphone in my pocket could transmit data to a cellphone in the pocket of a person with whom I was shaking hands. Similarly, I could authenticate my presence through a cellphone in my pocket that would transmit a signal to a computer I was touching.
The technology worked but it did not hit the market because of the cost of the transceiver and the alternative (cheaper) solution provided by Bluetooth.
Now at Washington University researchers are looking into a similar technology but trying to get rid of the transceiver.
Their idea is to leverage on smart phones fingerprint recognition or on touch screens. These sensors are used today to receive "signals" (from your fingers) but they can also double up as transmitter at relatively low frequency. In their research they demonstrated that it is possible to transmit some 50 bits per second in this way. Not much, but sufficient to send an authenticated "open" command through your body when you put a finger on your smartphone fingerprint sensor and your other hand onto the door knob (this latter, of course, needs to be upgraded and become smart to capture the signals flowing from your hand). Similarly, you can send authenticated messages to an insulin pump embedded in your tummy.
The interest for this kind of solution lies in the much higher security. A radio signal, such as the one used by WiFi and Bluetooth can be intercepted and used maliciously. Think about the number of cars that have been "hacked" by thieves lingering in a parking lot and waiting for a person to lock/unlock the car using a remote controller. That signal can be copied and reused to open the car (it is actually a bit more complex since cars manufactured use rolling codes but thieves are ingenious and have already found a work around).
You get pretty annoyed if someone hacks onto your car, just imagine how you would feel if someone would hack into your pacemaker....