- Pusan National stretchable OECT switches between logic and memory modes
- Salt concentration change eliminates need for multiple circuit components
- Device changes color from light to dark blue as operational status shifts
- Proof-of-concept compression bandage responds to edema and temperature
A stretchable organic electrochemical transistor developed at Pusan National University toggles between digital logic and analog memory functions by adjusting the salt concentration in its electrolyte. The device, detailed in ACS Nano Volume 20, Issue 26 in July 2026, eliminates the need to stack multiple components for sensing, processing, and storage—collapsing what typically requires separate circuits into one adaptable element.
Assistant Professor Hyunseok Shim’s team modified the conducting polymer PEDOT:PSS with two additives to boost electrical conductivity and stretch tolerance. Current through the device is controlled by ion injection from the electrolyte, driven by voltage applied to a gate electrode. High sodium chloride concentrations enable rapid ON/OFF switching for digital operations; lower concentrations produce analog memory behavior similar to neural synapses.
Color-shifting readout signals operational mode
The transistor’s operational state is visible to the naked eye. As the device switches modes, it shifts from light to dark blue, providing instant confirmation without electronic diagnostics. The team built a wearable patch that senses inflammatory edema and skin temperature, then automatically adjusts a compression band to prevent tissue damage. The patch demonstrates how a single soft device can both process and store physiological signals without added circuitry.
OECTs offer intrinsic flexibility, ion-to-electron conversion, low working voltage below 1 V, and large transconductance—features that suit wearable bioelectronics but typically require separate devices for logic and memory. PEDOT:PSS lacks elasticity in stretchable electronics, which is why the Pusan team added chemical modifiers to improve repeated-stretch performance. PEDOT:PSS has emerged as the most promising flexible electrode material over rigid metallic oxides, serving roles from transparent electrodes to motion-sensing conductors.
Reconfigurable transistors enable brain-like processing
The ability to reconfigure a single transistor between computing and memory modes aligns with broader efforts to replicate brain-like processing in hardware. Organic transistor-based artificial synapses and neurons are advancing into neuromorphic computing and neuromorphic sensing applications, with recent demonstrations highlighting bio-integrated systems. Neuromorphic computing seeks to replicate the computational efficiency and parallelism of the human brain by emulating neural architecture, and adaptive organic devices offer a path to low-power, flexible implementations.
One constraint engineers will encounter is the speed-versus-accuracy tradeoff when salt concentration governs switching behavior. Changing electrolyte composition is slower than purely electronic reconfiguration, which limits real-time responsiveness in applications that require rapid mode changes. Still, for physiological monitoring where signals evolve over seconds or minutes, electrolyte tuning offers a compelling simplification.
Autonomous pressure regulation simplifies wound care
Shim envisions autonomous personalized therapeutics—dynamic compression bandages and electronic skins that respond to injury in real time. The visible color change offers a practical monitoring feature that requires no power or display module. The technology could extend to soft robots and adaptive prosthetics that learn from their surroundings, provided manufacturing can scale the additive-modified polymer at consistent quality.
The proof-of-concept compression patch addresses a clinical need: edema monitoring and pressure regulation to prevent damage. Current solutions use fixed-pressure wraps or multi-component sensor arrays with separate logic boards, increasing bulk and power draw. A single reconfigurable transistor that stretches with skin and signals status visually streamlines both form factor and usability.
Pusan National’s salt-tuned OECT proves that a single stretchable device can replace multi-chip architectures in wearable health monitors. The color-shifting status indicator and elimination of separate logic and memory components reduce design complexity and power budgets. For engineers developing next-generation bioelectronics, the platform demonstrates a credible path to integrated sensor-processor patches that conform to skin and operate within the sub-1 V envelope required for safe, long-term wear. Watch for manufacturing scalability and electrolyte stability as the technology moves toward commercial validation.
How does salt concentration change transistor function in OECTs?
High sodium chloride concentrations accelerate ion migration through the polymer channel, enabling fast ON/OFF gating for digital logic. Lower salt levels slow ion movement, producing gradual conductance changes that mimic analog synaptic memory. The electrolyte chemistry directly controls whether the device acts as a switch or a learning element.
What limits PEDOT:PSS stretchability in wearable devices?
PEDOT:PSS forms rigid crystalline regions and stable π–π stacks during thin-film baking, making the dried polymer brittle under strain. Pusan researchers added two chemical modifiers to improve both electrical conductivity and mechanical compliance, allowing the transistor to survive repeated stretching without degrading performance or cracking the conductive channel.
Article Source: Pusan National University Reports an Adaptive Organic Transistor for Wearable Electronics
