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▲ [23p-A105-8] A breathable and stretchable sensor sheet design for wearable device
Keywords:wearable device, sensor sheet
Flexible devices have attracted much attention recently due to their portability, conformability, and so on. With the long-time wear application of flexible devices during daily life, the comfortability of wearing the device should be improved by optimizing the stretchability and breathability of the film because of perspiration from the skin. Aiming at the problems above, we propose a new design of a low-cost flexible screen-printed silver electrode with the kirigami structure on a PET film[1].
The maximum strain of the designed film is about 32%. The kirigami Ag electrodes were formed on PET film. The resistance changes of Ag resistance during repeatedly applying and releasing stretch 300 cycles ranging from 0 to 10% showed an overall upward trend, but the range of variation remained ±10%, which is sufficiently stable for daily application.
Breathability of this sheet by measuring water vapor transmission rate and mechanical adhesive were characterized. The film with kirigami structure exhibits superior water vapor permeability even better than the pure PU membrane. And even after attaching and removing the film 1000 times, the film still maintained its adhesiveness. Furthermore, breathability difference between a PET film w/wo kirigami was investigated by measuring impedance change of skin surface caused by sweat. This clearly shows that optimized kirigami design makes good breathability and less sweat perspiration.
Finally, a breathable ECG sensor system was fabricated to measure long-term, continuous ECG signals wirelessly during daily activities as a proof of concept. Whether applied to different scenarios such as sports, ECG signals can be stably recorded. This is due to the good breathability and stretchability of the kirigami design, proving that this sheet has a wide range of wearable applications.
Reference [1] Y. Xuan et al., Applied Physics Reviews, 9, 011425, 2022.
The maximum strain of the designed film is about 32%. The kirigami Ag electrodes were formed on PET film. The resistance changes of Ag resistance during repeatedly applying and releasing stretch 300 cycles ranging from 0 to 10% showed an overall upward trend, but the range of variation remained ±10%, which is sufficiently stable for daily application.
Breathability of this sheet by measuring water vapor transmission rate and mechanical adhesive were characterized. The film with kirigami structure exhibits superior water vapor permeability even better than the pure PU membrane. And even after attaching and removing the film 1000 times, the film still maintained its adhesiveness. Furthermore, breathability difference between a PET film w/wo kirigami was investigated by measuring impedance change of skin surface caused by sweat. This clearly shows that optimized kirigami design makes good breathability and less sweat perspiration.
Finally, a breathable ECG sensor system was fabricated to measure long-term, continuous ECG signals wirelessly during daily activities as a proof of concept. Whether applied to different scenarios such as sports, ECG signals can be stably recorded. This is due to the good breathability and stretchability of the kirigami design, proving that this sheet has a wide range of wearable applications.
Reference [1] Y. Xuan et al., Applied Physics Reviews, 9, 011425, 2022.