Printable elastomeric electrodes with sweat-enhanced conductivity for wearables.

Area of Science:

• Materials Science
• Electrochemistry
• Wearable Technology

Background:

• Developing conductive materials for wearable electronics is crucial.
• Existing materials often lack conductivity enhancement mechanisms for on-body applications.
• Printable and stretchable electrodes require robust binder materials.

Purpose of the Study:

• To synthesize a thermoplastic and hydrophilic poly(urethane-acrylate) (HPUA) binder.
• To create printable and stretchable silver flakes-HPUA (Ag-HPUA) electrodes.
• To investigate sweat-induced conductivity enhancement in Ag-HPUA electrodes.

Main Methods:

• Rational synthesis of HPUA binder.
• Fabrication of printable and stretchable Ag-HPUA electrodes.
• Evaluation of electrode resistance changes in response to human sweat.
• Construction of a sweat-activated battery using Ag-HPUA electrodes.

Main Results:

• Ag-HPUA electrodes exhibit conductivity enhancement upon exposure to human sweat.
• Synergistic effect of Cl- and lactic acid in sweat removes surfactant and promotes silver sintering.
• Electrode resistance decreased from 3.02 to 0.62 ohm during 27 minutes of sweating.
• A functional sweat-activated battery was demonstrated using these electrodes.

Conclusions:

• Human sweat can significantly enhance the conductivity of Ag-HPUA electrodes.
• This sweat-activated conductivity mechanism offers a novel approach for wearable electronics.
• The developed Ag-HPUA electrodes provide meritorious insights for designing advanced wearable devices.