# Uncharged Monolithic Carbon Fibers Are More Sensitive to Cross-Junction Compression than Charged

## TL;DR

This paper shows that charged carbon fibers used in wearable textiles can adjust their sensitivity to pressure, which could improve health monitoring in smart clothing.

## Contribution

The study introduces controllable sensitivity in monolithic carbon cloth electrodes through electrolyte saturation and charging.

## Key findings

- MACCE conductance increased by 29% when saturated with Na2SO4 and charged to 0.375 V.
- Electrode sensitivity decreased by 30% at the highest charge due to repulsive forces in the electrical double layer.
- Controllable sensitivity can help wearable garments avoid irrelevant signals and focus on essential health changes.

## Abstract

Textile-based wearable robotics increasingly integrates sensing and energy materials to enhance functionality, particularly in physiological monitoring, demanding higher-performing and abundant robotic textiles. Among the alternatives, activated carbon cloth stands out due to its monolithic nature and high specific surface area, enabling uninterrupted electron transfer and energy storage capability in the electrical double layer, respectively. Yet, the potential of monolithic activated carbon cloth electrodes (MACCEs) in wearables still needs to be explored, particularly in sensing and energy storage. MACCE conductance increased by 29% when saturated with Na2SO4 aqueous electrolyte and charged from 0 to 0.375 V. MACCE was validated for measuring pressure up to 28 kPa at all assessed charge levels. Electrode sensitivity to compression decreased by 30% at the highest potential due to repulsive forces between like charges in electrical double layers at the MACCE surface, counteracting compression. MACCE’s controllable sensitivity decrease can be beneficial for garments in avoiding irrelevant signals and focusing on essential health changes. A MACCE charge-dependent sensitivity provides a method for assessing local electrode charge. Our study highlights controlled charging and electrolyte interactions in MACCE for multifunctional roles, including energy transmission and pressure detection, in smart wearables.