Skin-mounted electronics could help to monitor muscle activity

The field of wearable electronics has taken an important step forward with an ultra-thin device platform that can be mounted directly onto human skin, in a similar manner to a temporary tattoo.

Engineers at the University of Illinois at Urbana-Champaign developed a device geometry they call ‘filamentary serpentine’, in which the circuits for the various devices are fabricated as tiny, squiggled wires that can bend, wrinkle and stretch with the mechanical properties of skin. The device patches are initially mounted on a thin sheet of water-soluble plastic, then laminated to the skin with water.

Skin-mounted electronics have many biomedical applications, including electro-encephalography (EEG) and electromyography (EMG) sensors to monitor nerve and muscle activity.

‘If we want to understand brain function in a natural environment, that’s completely incompatible with EEG studies in a laboratory,’ said co-leader of the project Prof Todd Coleman of Illinois. ‘We think this could be an important conceptual advance in wearable electronics, to achieve something that is almost unnoticeable to the wearer.’

The researchers have so far demonstrated their concept with a diverse array of electronic components including sensors, light-emitting diodes, transistors, radio-frequency capacitors, wireless antennas and conductive coils and solar cells for power.

They use simple adaptations of techniques used in the semiconductor industry so the patches are easily scalable and manufacturable, and a device company, mc10, has been founded to commercialise certain versions of the technology.

Now the researchers are working to integrate the various devices mounted on the platform so that they work together as a system, rather than individually functioning devices, and to add Wi-Fi capability.

‘The vision is to exploit these concepts in systems that have self-contained, integrated functionality — perhaps ultimately working in a therapeutic fashion with closed feedback control based on integrated sensors, in a co-ordinated manner with the body itself,’ said Prof John Rogers, also of Illinois, who co-led the project with Coleman.