Eutectogels as a Semisolid Electrolyte for Organic Electrochemical Transistors

Area of Science:

• Materials Science
• Electronics
• Biomedical Engineering

Background:

• Organic electrochemical transistors (OECTs) are promising for detecting weak biological signals due to high amplification.
• While OECTs often use aqueous electrolytes, solid-like gels are ideal for wearable electrophysiology probes.
• The influence of gel electrolyte type and composition on OECT performance remains unclear.

Purpose of the Study:

• To investigate the impact of different gel electrolytes (hydrogels, eutectogels, iongels) on OECT performance.
• To determine optimal device design considerations for specific electrolytes.
• To evaluate the stability and signal quality of OECTs with eutectogel electrolytes for physiological monitoring.

Main Methods:

• Fabrication and testing of OECTs using three gel electrolyte types: hydrogels, eutectogels, and iongels.
• Characterization of transient and steady-state device performance.
• Evaluation of operational stability using simulated electrocardiogram (ECG) recordings over extended periods (5 hours and 30 days).

Main Results:

• Eutectogels, specifically those with poly(glycerol 1,3-diglycerolate diacrylate) and choline chloride/1,3-propanediol deep eutectic solvent, demonstrated superior performance over hydrogels and iongels.
• Eutectogel-based enhancement mode OECTs showed exceptional operational stability with no signal-to-noise ratio (SNR) variation during continuous and long-term recordings.
• Eutectogel OECTs yielded higher ECG signal amplitudes and SNR compared to commercial hydrogel-based devices.

Conclusions:

• Eutectogels represent a highly effective semisolid electrolyte for OECTs.
• These findings support the use of eutectogels in wearable devices for robust and prolonged physiological signal monitoring.
• Eutectogel-based OECTs offer a significant advancement over current technologies for cutaneous electrophysiology.