Elasticity (physics)

Internal medicine

Engineering

Fabrication

Pathology

Physical chemistry

Composite material

Biosensor

Nanotechnology

Electrode

Organic chemistry

Chemistry

Materials science

Electrical conductor

Alternative medicine

Sensitivity (control systems)

Ionic bonding

Electronic engineering

Gauge factor

Strain (injury)

Conductor

Optoelectronics

Bioelectronics

Strain gauge

Medicine

Advanced Functional Materials

Stretchability and sensitivity are essential properties of wearable electronics for effective motion monitoring. In general, increasing the sensitivity of strain sensors based on ionic conductors trades off elasticity, which results in low sensitivity of the strain sensors at large mechanical deformations. To address this, ion‐permeable conducting polymer electrodes with low contact resistance are utilized in ionic gel‐based strain sensors. Using a rectangular‐shaped ionic gel and ion‐permeable electrodes significantly increase the gauge factor of the strain sensor, similar to the theoretical value at a given strain. To further increase the sensitivity of the strain sensor, the ionic gel is patterned with zigzagged tracks that gap apart as the gel stretches, and the gaps close as the gel contracts, leading to a large variation in the relative resistance upon stretching. By combining the zigzagged ionic gel and the ion‐permeable electrodes, highly sensitive stretchable sensors are realized with a record‐high gauge factor of 173, compared to existing ionic conductor‐based stretchable strain sensors. The zigzag‐patterned ionic sensor can successfully monitor various motions when attached to the human body. These results are expected to afford promising strategies for developing highly sensitive, stretchable sensing systems for E‐skin sensors and soft robotics.

Ultra‐Sensitive and Stretchable Ionic Skins for High‐Precision Motion Monitoring