Researchers at the University of Tokyo have created an ultrathin, ultraflexible film layer that will enhance e-skin display. The protective layer includes an air stable organic light emitting diode (OLED) that can be used for athletes as well as patients in hospitals to create electronic skin displays of blood oxygen levels, temperature, heart rate and more.

The new film overcomes the limitations of current wearables, such as millimeter thicknesses on glass or plastic substrates with low flexibility, or micrometer devices that are too thin to survive in air.

Thin film blood oxygen level monitor. Credit: Someya LaboratoryThin film blood oxygen level monitor. Credit: Someya LaboratoryUsing alternating layers of inorganic silicon oxynitrite and organic parylene materials, the scientists were able to develop a high-quality protective film less than two micrometers thick. The film prevents oxygen and water from passing into the air, extending the life of the film from the current few hours to several days. They were also able to attach a transparent indium tin oxide (ITO) electrodes to the ultrathin substrate without damage. The team then created polymer light-emitting diodes (PLEDs) and organic photodetectors (OPDs), at three micrometers thick, thin enough to attach to the skin and flexible enough to distort in response to movement.

The PLEDs were over 6 times more efficient than previous versions: reducing heat generation and power consumption which made them highly suitable for direct attachment to the body for medical applications. The team even combined red and green PLEDs with a photodetector in order to demonstrate a blood oxygen sensor.