Spiders possess a remarkable ability to not only detect external signals with high sensitivity but also modulate the sensitivity of their sensory organs by adjusting the leg posture. Specifically, a spider's slit organ, which detects physical deformation or strain, is insensitive in the closed leg state and highly sensitive in the extension state, resulting in a difference of 224 times in sensitivity. This ability to adjust sensitivity has garnered attention from researchers who seek to improve the wide-ranging and enhanced detection capabilities of other biological sensory systems.

Recent advances in mechanosensory technology have enabled the development of highly sensitive and flexible devices that can measure a range of physical stimuli, such as strain, pressure, and vibration. However, a tradeoff exists between measurement range and sensitivity for each sensor, necessitating different sensors depending on the target signal. This physical limitation is also present in nature, such as the action potential firing rate in the nervous system.

To address this issue, researchers have developed the Tunable, Ultrasensitive, Nature-inspired, Epidermal Sensor (TUNES), which is inspired by the spider's sensory system. The TUNES sensor can adjust its sensitivity by preset strain, resulting in dramatically increased sensitivity for the pressure regime of the signal. This tunability arises from the nonlinear characteristics of the nanoscale-crack-based sensor used.

The TUNES sensor can measure diverse biosignals, such as respiration, muscle contraction/relaxation, and minute wrist pulse, and has shown potential for biomedical applications through comparison with a commercial medical device in a clinical trial. Additionally, the TUNES sensor has demonstrated the ability to diagnose and monitor human health in the future through machine learning, as shown by its successful classification of pulse signals from Young and Old groups. The TUNES sensor represents a promising step towards developing highly sensitive and tunable sensors with broad applications in the biomedical field.

The original article can be found here:

Kim, T., Hong, I., Roh, Y. et al. Spider-inspired tunable mechanosensor for biomedical applications. npj Flex Electron 7, 12 (2023).

https://doi.org/10.1038/s41528-023-00247-2