Developing the human cable

The picture of Ericsson’s CEO transferring a picture from his telephone to his computer via his own body has been cabled around the world. The technology comes from Linköping University (LiU) and is now being further developed by J. Jacob Wikner of the Division for Electronics Systems at LiU.

Ericsson CEO Hans Vestberg attracted a lot of attention in mid-January at the large consumer exhibition CES in Las Vegas when he became a human cable. A picture was transferred from the phone he held in his left hand to a computer he was touching with his right hand.

The audience did not fail to react, and you can’t get much more attention than that for thesis work. The technology is, in fact, the result of three thesis jobs at Linköping University, supervised by J. Jacob Wikner, university lecturer in Electronics Systems.
The assignment itself, to develop a sensitive receiver that manages to receive the weak signals that come from us as human cables, originally came from Jan Hederén, strategist at Ericsson Radio.

With the increased use of social media, we are expected to want new social functions and people like to touch things with their hands. The basic idea here is to create this type of natural interaction by using the capacitive phenomenon already in our bodies, and in all organic material.
Hederén has, however, been clear that this is not about developing a new product for Ericsson, but rather to show the market what is possible as regards creating an extremely simple interaction with the environment. This is something that, it is hoped, will increase the benefits of mobile networks, while at the same time providing new kinds of smart phones.
Wikner is continuing along the trail being blazed, with the goal in a few years of being able to send a small video via the body at 10 Mbit/sec.

“Nothing more than this may ever be needed,” he asserts.

Other technologies are both more efficient and quicker when larger amounts of data than this are to be transferred. But with this transfer technology, it could be possible to unlock a car when the handle is gripped, transfer a business card from my telephone to the person I’m shaking hands with, or transfer the code when I’m making a payment via the Internet.

“Smart phones have opened up this possibility for local communication,” Wikner states.

That capacitive signals from the human body can be read has been long known; they are used in medical applications such as EEG, where electric activity in the cerebral cortex is measured. These kinds of circuits were developed in places like the Division of Electronic Devices at LiU.
In Great Britain, a bandage is being marketed that can, among other things take the patient’s pulse and send it and other data about their condition, to the health care centre. There are more examples, but the difference is that now people are looking at two-way communication, while previously it was simply an issue of measurement technology and data collection.

However there are many weak signals sent through the human body; it’s an issue of a solitary volt from the transmitter, and the signal lowers significantly on its way from the palm of one hand to another.

“If a couple of volts are sent, only a microvolt is involved at the other end. A current isn’t sent through the body, either; it only affects the electrical field and redistributes the charge,” Wikner says.

There is also a very, very sensitive receiver at the terminal.

“Strategically, it’s a low-risk project. The sensitive receiver we’ll be developing will still be of use, even if this technology doesn’t make an impact. We’ll also develop a device that can be integrated into the telephone; that work will also be of use,” he says.

Wikner’s research project is called Transceivers for Body-Area Network Communication, and is funded by the LiU research organisation CENIIT. CENIIT employs Wikner part-time, Muhammad Irfan Kazim as a doctoral student and, to start with, six students who will complete their degree work in the field.

“It’s about developing a whole system, with hardware, a mobile app, and even components at the silicon level,” he says.

Additionally, the project includes studying whether it can be in any way harmful to transfer data via the human body.

“We’re relatively sure it’s not; this deals with very low fields, well under the limits set up for Radio-frequency identification tags (RFID), for example, which are becoming more and more common and studying this more closely is also part of the project."

Where have the students gone who did their degree work on behalf of Ericsson?

“The work was carried out by three Indian students: Dilip Kumar Vajravelu, Bibin Babu and Kiran Kariyannavar. They had exactly the right combination of interests. The degree work was ready last autumn, but was kept secret until the patent applications were ready,” Wikner says.
“And Ericsson employed them immediately.”

Transceivers for body-area network communication

The social media, the usage of smart mobile phones and wider coverage of mobile networks is shrinking down our world in terms of connecting people. The six-handshakes-away "theory" becomes more and more viable.

Since recently, so called near-field communication (NFC) is finding its way into the smart phones and a new infrastructure with respect to communication between humans and devices is being built up. The NFC typically relies on the widely used RFID technique. The RFID technique does indeed come with different operation principles, but the most dominating ones are inductive and microwave-based coupling techniques. The inductive principles uses a coil to generate/absorb a magnetic field. In this way, data can be transmitted/received between two or more devices. The technique is "old" in the sense that is is found in securtiy systems (entrance systems, shop lifting, etc.) and logistics (package tracking, etc.). Recently, however, the NFC is extending this concept in other applications, such as flight check-in, and more.

The suggested techniques, however, are typically limited in two ways: the transmission speed is relatively low (well...) and operation relies on the need to take your smart phone out of your pocket and keep close to a transceiver. The applications are still oriented towards the transfer of your ID, a short key of some kind, or similar.

Our project has a slightly different scope with focus on the transceivers of such communication scenarios; first of all, we are aiming for higher data rates and secondly we are looking to use the human body as a communication channel. This combination of NFC with body area network (BAN) is going to increase the number of applications, but on the other hand, it is also going to put tougher requirements on the transceiver specifications.

A twist in this scenario is that the body channel does not offer an inductive interface, instead it is capacitive.

Vision and industrial motive

The strongest motivation which would be given in favour of capacitive/inductive coupling transceivers is; cell-based communication systems, which forms the core of today's mobile/wireless communications, are no longer able to meet the requirements of increased level of information/multimedia sharing among the users of smart devices because of the limited number of frequency carriers and almost the completion of the frequency allocation table. That is why big companies, like Apple and Google, are also looking forward towards these transceiver architectures as viable means of next-generation touch-and-go communication.

In a world, where it is imagined that our ambiance would also be soon intelligent along with a scenario where each person in the world would be wearing five to ten cheap sensor nodes able to intelligently communicate with each other or with the personal CPU, it will not be possible to assign or allocate different carrier frequencies for every device or individual. So the only viable solution to make this a realizable dream is; we develop transceivers based on capacitive/inductive coupling. The applications which could be built up around the basic theme of capacitive/inductive transceivers could have many forms, a few of them just listed below;

• Low power Escalators which turn on inductively/capacitively when the user comes in its close vicinity
• New door (un)locking systems which use inductive/capacitive coupling-based transceivers
• Inductive/capacitively coupled photocopier, fax, printers
• Electronic money transfer (a mass phenomenon)
• Human body channel using inductive/capacitive coupling-based transceivers for communication between wearable sensors
• Capacitively-coupled touch panels with intelligent lighting layouts for easily switching on the lights,
• IP-based smart dust motes using capacitive/inductive coupling mechanism for information transfer
• Mobile-to-Mobile or Machine-to-Machine transfer of information
• Intelligent gaming consoles using capacitive/inductive coupling based transceivers
• Multimedia transfer (high fidelity sound and high definition video)

Any of these suggested topics (and some being already established using other means of communication), we believe, will be strong drivers for the project and attractive to industry and the research community.