Recently, researchers from the Tokyo University of Science developed electrodes for efficient human body communications and determined that they are safe for use. What is Human Body Communications, how did the researchers develop their electrodes for device communication, and how could HBC be used in the future?

What is Human Body Communications?

For short, Human Body Communications, or HBC, describes various methods for using the human body as a communication medium between two devices. Generally speaking, HBC refers to one of two electrical signal types; galvanic (i.e. current) and capacitive. Galvanic signals use a current flow through the body to represent information, while a capacitive signal induces electric fields that travel through the body.

The human body can act as a transmission medium thanks to its high water and ion content. Considering that the human body relies on electrical signals to function, it would make sense that this exact mechanism can be exploited and manipulated for signal transport between worn devices.

While HBC systems have been designed and proven to work, there is some concern that the use of such signals could interfere with bodily functions. Nerves in the human body utilise electrical signals (ion transport) to send signals, but electrical current can be used for other tasks. For example, electrical signals passed through broken bones encourage faster healing, and researchers have exploited this to create implantable electrodes that can heal bones faster. Therefore, researchers need to be careful not to interfere with bodily functions and use signals ignored by biological functions.

Researchers determine human tissue to be suitable for data communication

Recently, researchers from Tokyo University conducted a series of experiments to determine the viability of human tissue as a signal medium. Current wearable devices utilise wireless signals in the form of Bluetooth and Wi-Fi, but these come with multiple disadvantages, including high power consumption and susceptibility to interference. As such, the team decided to develop electrodes that would reliably transmit information through the human body while remaining immune to other HBC systems.

The first step in the researcher’s work involved choosing a device that would benefit from an HBC. In this case, binaural hearing aids were chosen. They work in pairs and require hearing aids to work in sync (presenting many signal challenges, including propagation, signal strength, and reflections).

The second step was to calculate the input impedance of electrodes and the characteristics of the human body (such as electric field distribution). Once the simulation model was calibrated, the researchers moved to alter the electrodes to maximise their performance.

The results showed that the best electrode designs are those that have matching reactive impedances. Furthermore, the results also showed that the system designed was highly immune from nearby HBC systems on others. This allows for individuals to be close to each other without interfering with their communication systems. The researchers also demonstrated that the levels of electromagnetic exposure are well below what humans can tolerate and determined that their system is perfectly safe for use on humans.

Could HBC be used in the future?

HBC could likely be a solution for worn devices in the future for several reasons. Firstly, HBC is primarily immune to other HBC systems not in direct contact, meaning that device density and data rates can be maximised without interference.

Secondly, HBC could allow two users to interact through physical touch, which could open the world to a new form of networking. A single handshake between two HBC users could transfer all kinds of information, including contact details, daily logs, and even private information such as passcodes, to a property.

Thirdly, the low energy consumption of HBC enables smaller wearable devices to communicate across the body without requiring significant power sources (assuming that the device is battery operated). The ability to transmit information through the body also eliminates wires, thereby making wearable devices comfortable.

HBC is in its infancy, and it presents engineers with a whole range of potential. Individuals could become their local area network, introducing a whole new type of computing device that only requires a human touch to operate.