There has been little exploration of the use of organic electrochemical transistors (OECTs) in pressure sensors because OECTs are usually paired with liquid gating substances, which do not respond well to external pressure. A team has found ways to solve this problem.
They first experimented with a solid type of gating substance — a charged, gelatinous substance called an ionic hydrogel. Due to the physical characteristics of this gel, they were able to demonstrate improved pressure sensing when they used it together with OECTs. The team fabricated ionic hydrogels with tiny pyramidal microstructures, which helped to increase the pressure sensitivity that could be measured. The deformity of the hydrogel microstructures in response to applied pressure increases the capacitance change at the gate electrodes, enhancing the ability to detect very subtle pressure signals.
The team also found that the microstructured hydrogel allowed them to obtain higher pressure sensitivity that could be adjusted by changing the applied gate voltage. Furthermore, this optimized sensor could operate at low operation voltage and low power consumption. These features combine to make a high-performing pressure sensor that is economical, long-lasting, and energy efficient — clear advantages for devices that are intended to collect long-term, real-time data.
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