The prototype described in a presentation titled “Continuous health-monitoring with ultraflexible on-skin sensors” consists of gold nanomesh-based breathable skin sensors and an elastic display that fits snugly on the skin, so recorded data (such as an electrocardiogram or temperature) can be made readily visible for the patient. Combined with a wireless communication module, this integrated biomedical sensor system could transmit biometric data to the cloud for physicians to monitor.
The skin display, developed in cooperation with Dai Nippon Printing (DNP) consists of a 16×24 array of red microLEDs (1×0.5mm in size) and screen-printed stretchable silver wiring mounted onto a rubber sheet. Only 1mm thick, it can be stretched to 45% of its original size, taking its 16×24 pixels from a 38×58mm2 effective display area to 64×96mm2 when stretched, with pixel pitch increasing from 2.4mm when contracted to a maximum of 4.0mm when extended.
The stretchable display is addressed at 2V by a passive matrix and can be refreshed at 60Hz, fast enough for any biomedical data or to run small messaging animations that compassionate relatives may want to send to the patient.
Someya was keen to highlight that the new display was far more resistant to the wear and tear of stretching than previously reported wearable displays.
“It is built on a novel structure that minimizes the stress resulting from stretching on the juncture of hard materials, such as the micro LEDs, and soft materials, like the elastic wiring—a leading cause of damage for other models”, he says.
During stretching tests, and while being worn on a contracting hand, not a single pixel failed. As for the nanomesh skin sensors (see Gold nanomesh enables ultra-breathable skin electronics), because they are breathable, they can be worn on the skin continuously for a week without causing any inflammation. With their gold-nanomesh skin electronics, the researchers were able to sense temperature, pressure, myoelectricity and even record an electrocardiogram.
The skin sensor and skin displays were developed separately and Someya admits that the breathability of the skin display has yet to be improved (it is made of a continuous film for now). One way to do it may simply be to engineer holes through the rubber substrates, he hinted in an email exchange with eeNews Europe.
In his talk, Someya raised the issue of global aging and the inevitable shortage of skilled workers in the medical and nursing sectors, as well as potentially soaring medical expenses. According to Moody’s, 13 countries will be super-aged by 2020 and 34 countries by 2030. Japan has already entered the super-aged society, the percentage of those aged 65 and over was 27.3% in 2017 and will cross 30% in 2025.
He sees the newly-developed skin electronics system as a way to enhance information accessibility for the elderly or the infirm for whom using existing devices and interfaces may prove difficult.
Such a wearable system could also ease the strain on home healthcare systems in aging societies through continuous, non-invasive health monitoring and self-care at home.
Although it has to improve the reliability of the stretchable device through structure optimization, Dai Nippon Printing is looking to bring the integrated skin display to market within the next three years.
The researcher expects such a skin-display to find other applications in industry, fashion but also sports coaching.