Adrica Kyndiah

Advances in understanding biological excitability have driven both mathematical modeling and hardware emulation of action potential generation and propagation. While neuromorphic devices based on inorganic or organic systems have advanced rapidly, cardiomorphic hardware remains largely unexplored due to the complexity of reproducing multiple ionic dynamics and the temporal mismatch between the slow cardiac activity and the fast operation of solid-state electronics. Here, we present an organic electrochemical cardiomyocyte (OECM) in which ion-mediated channel currents exhibit time constants aligned with those of ventricular ionic processes. By reproducing a fast sodium current alongside slow, interdependent calcium and potassium currents, the OECM generates ventricular-like action potentials with biorealistic phases, displays refractoriness and responsiveness to electrical or chemical modulation, and synchronizes with bioelectric signals from living cardiomyocytes. These results shift the paradigm of cardiac modeling from purely computational simulations toward biorealistic hardware emulation.

Organic bioelectronic transistors emerged as powerful tools for probing cellular electrophysiology, offering biocompatibility, mechanical softness, and operational stability in biological environments. Despite these advantages, device benchmarking focused so far exclusively on electrical figures of merit, leaving interfacial processes that contribute to signal recording fidelity largely unexplored. Poly[2‐(3,3′‐bis(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)‐[2,2’‐bithiophen]‐5‐yl)thieno[3,2‐b]thiophene] (p(g2T‐TT)) is a model glycolated organic mixed ionic‐electronic conductor, whose high transconductance and optimal volumetric field‐effect behavior in physiological environment have been widely documented in Organic Electrochemical Transistor (OECT) configurations. Thus, p(g2T‐TT)‐based OECT was assessed as a promising candidate for recording action potentials (APs) from human induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs). Surprisingly, although AP signal transduction was observed, the recorded AP waveforms failed to reproduce the expected morphology, especially when compared to signals recorded via poly(3‐hexylthiophene‐2,5‐diyl) (P3HT)‐based Electrolyte‐Gated Field‐Effect Transistors (EGOFETs). Immunofluorescence imaging revealed improved adhesion on P3HT with respect to p(g2T‐TT), suggesting weaker cell‐device coupling as the underlying limitation. Our results show that not all polymers combining biocompatibility and high electrical performance can transduce AP signals with high‐fidelity. Instead, interfacial properties govern bioelectronic transduction and provide a foundation for the rational design of polymers and platforms enabling reliable in vitro cellular electrophysiology, with potential translation to in vivo applications.

Mixed ionic-electronic conductors host tightly coupled interactions among mobile ions, electronic charges, and the polymer matrix, giving rise to complex multimodal responses spanning electrical, mechanical, and morphological transformations. These materials underpin organic electrochemical transistors (OECTs), which translate such interactions into low-voltage signal amplification and sensing for applications in bioelectronics, neuromorphic computing, and memory. Despite their central role, OECT current-voltage transfer characteristics are often treated phenomenologically, as both the local multimodal dynamics and their connection to global device response remain unresolved. Here, we reveal that the transfer curve encodes a cascade of spatially localized electrochemical transitions, each associated with distinct changes in conductivity, stiffness, and morphology, fundamentally redefining it as a spatially resolved fingerprint of device's internal state. Using automated operando multimodal in-liquid scanning dielectric microscopy, we directly map these dynamics and identify region-specific electrochemical thresholds governing the interplay between source, channel, and drain. We found that the local tip-sample electrostatic force serves as a remarkable mechanistic observable of coupled multimodal dynamics in mixed conductors. A physically grounded model links it to general material, interfacial, and geometric parameters, enabling mechanistic interpretation and predictive insights. Our work provides a new framework for probing and understanding mixed conduction in ion-electron coupled systems.

Scalable and high-throughput platforms to non-invasively record the Action Potentials (APs) of excitable cells are highly demanded to accelerate disease diagnosis and drug discovery. AP recordings are typically achieved with the invasive and low-throughput patch clamp technique. Non-invasive alternatives like planar multielectrode arrays cannot record APs without membrane poration, preventing accurate measurements of disease states and drug effects. Here, we disclose reliable and non-invasive recording of APs with patch clamp-like quality from human stem cell-derived cardiomyocytes using an inkjet-printed polymer semiconductor in an Electrolyte-Gated Field-Effect Transistor configuration. High sensitivity is proven by the detection of drug-induced pro-arrhythmic membrane potential oscillations as early/delayed afterdepolarizations. The higher throughput potential of this platform could significantly enhance disease modelling, drug screening, safety pharmacology and the study of abiotic/biotic interfaces.

Copper(II) phthalocyanine (CuPc), also known as Pigment Blue 15, is a widely utilized pigment renowned for its exceptional semiconducting properties when refined to electronic‐grade purity. Recent studies have confirmed its safety if ingested at doses required for essential active components in edible electronics for advanced gastrointestinal tract monitoring. Since in‐body operations impose stringent safety constraints on operational biases, the development of transistors with high transconductance at low voltages is required to ensure adequate amplification gain. This study presents a simple and cost‐effective method for producing solution‐processed CuPc films characterized by a unique porous microstructure that facilitates efficient volumetric ion uptake and mixed ionic‐electronic conductivity in electrolyte‐gated devices. These porous films exhibit capacitance 30 times greater than compact CuPc films produced through conventional physical vapor deposition methods. The resulting edible transistors demonstrate On/Off ratios exceeding 10 ³ and channel width‐normalized transconductance of up to 50 µS mm ⁻¹ at 0.8 V, establishing their potential as critical active components in future edible devices. Moreover, the proposed method results in a limited impact of impurities on CuPc charge transport efficiency, thus affecting the purification costs and, crucially, enabling the sourcing of CuPc pigments through recycling and upcycling.

The proliferation of distributed microelectronics and sensors necessitates adaptable, scalable, and cost‐effective power supplies. Organic thermoelectric generators (TEGs) that promise to harness heat sustainably and cost‐effectively are seen as pivotal elements in shaping future sensor infrastructures. Recent strides in morphological control through the alignment of conjugated polymer backbones have enhanced the thermoelectric performance of doped organic semiconductors to record values, matching expectations for real applications. However, the hurdles in crafting and deploying organic TEGs effectively exploiting aligned polymer films remain unexplored. This work presents a design and fabrication method to incorporate aligned films into a thin label‐like TEG. Thin films of regioregular poly(3‐hexylthiophene) (P3HT) and poly(2,5‐bis((7‐butoxyheptyl)thiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT‐⁸O) are aligned via high‐temperature rubbing technique inducing a high degree of anisotropy in their charge transport properties. The crystal structure and anisotropy of the films are exploited to realize monolithic TEGs by patterning conductive thermoelements via local inkjet doping of films transferred on ultrathin parylene substrates. The TEGs based on aligned P3HT and PBTTT‐⁸O exhibit exceptional TEG power factors of 0.33 and 1.04 nW cm⁻² K⁻², respectively. Lastly, as a proof‐of‐concept use case for the TEGs, a thermoelectrically‐powered volume‐indicating label is presented as a potential application in the healthcare and food industries.

The dissemination of sensors is key to realizing a sustainable, ‘intelligent’ world, where everyday objects and environments are equipped with sensing capabilities to advance the sustainability and quality of our lives—e.g. via smart homes, smart cities, smart healthcare, smart logistics, Industry 4.0, and precision agriculture. The realization of the full potential of these applications critically depends on the availability of easy-to-make, low-cost sensor technologies. Sensors based on printable electronic materials offer the ideal platform: they can be fabricated through simple methods (e.g. printing and coating) and are compatible with high-throughput roll-to-roll processing. Moreover, printable electronic materials often allow the fabrication of sensors on flexible/stretchable/biodegradable substrates, thereby enabling the deployment of sensors in unconventional settings. Fulfilling the promise of printable electronic materials for sensing will require materials and device innovations to enhance their ability to transduce external stimuli—light, ionizing radiation, pressure, strain, force, temperature, gas, vapours, humidity, and other chemical and biological analytes. This Roadmap brings together the viewpoints of experts in various printable sensing materials—and devices thereof—to provide insights into the status and outlook of the field. Alongside recent materials and device innovations, the roadmap discusses the key outstanding challenges pertaining to each printable sensing technology. Finally, the Roadmap points to promising directions to overcome these challenges and thus enable ubiquitous sensing for a sustainable, ‘intelligent’ world.

Electrolyte‐gated organic transistors (EGOTs) leveraging organic semiconductors' electronic and ionic transport characteristics are the key enablers for many biosensing and bioelectronic applications that can selectively sense, record, and monitor different biological and biochemical processes at the nanoscale and translate them into macroscopic electrical signals. Understanding such transduction mechanisms requires multiscale characterization tools to comprehensively probe local electrical properties and link them with device behavior across various bias points. Here, an automated scanning dielectric microscopy toolbox is demonstrated that performs operando in‐liquid scanning dielectric microscopy measurements on functional EGOTs and carries out extensive data analysis to unravel the evolution of local electrical properties in minute detail. This paper emphasizes critical experimental considerations permitting standardized, accurate, and reproducible data acquisition. The developed approach is validated with EGOTs based on blends of organic small molecule semiconductor and insulating polymer that work as accumulation‐mode field‐effect transistors. Furthermore, the degradation of local electrical characteristics at high gate voltages is probed, which is apparently driven by the destruction of local crystalline order due to undesirable electrochemical swelling of the organic semiconducting material near the source electrode edge. The developed approach paves the way for systematic probing of EGOT‐based technologies for targeted optimization and fundamental understanding.

The analytical physical modeling of undoped electrolyte gated organic field effect transistors (EGOFETs) in the Helmholtz approximation is presented. A compact analytical model for the current–voltage (I–V) characteristics, which includes the effects of the access series resistance, has been derived and validated by means of 2D finite element numerical calculations. The model describes all operating regimes continuously (subthreshold, linear, and saturation regimes), covers channel lengths down to a few micrometres and only includes physical device parameters. From the model, analytical expressions have been proposed for all the phenomenological parameters (e.g., capacitance, threshold voltage, sub‐threshold slope voltage, and sub‐threshold capacitance) appearing in the commonly used ideal FET model. The derived analytical physical model provides a simple and quantitative way to analyze the electrical characteristics of EGOFETs and EGOFET biosensors beyond the use of the oversimplified and phenomenological ideal FET model.

This work presents the analytical physical modeling of undoped organic metal‐electrolyte‐semiconductor (OMES) capacitors in the framework of the Nernst–Planck–Poisson theory, including the presence of compact interfacial layers. This work derives an exact analytical solution, up to a quadrature, for the stationary electric potential and charge density distributions in both the semiconductor film and the electrolyte solution, and from them the sheet semiconductor charge and the stationary differential capacitance are obtained as a function of the applied voltage. The dependence of these magnitudes on the physical device parameters, like the ionic concentration of the electrolyte, the capacitance of the interfacial compact layers and the injected hole density is then analyzed. This work shows that ionic diffusive effects in the electrolyte can play an important role in the device response, inducing a broadening of the transition from the weak to the strong accumulation regimes. This fact can make that the strong accumulation regime is not achieved in OMES within the usual voltage operation range of these devices. The analytical solution is validated by means of finite element numerical calculations. The implications of the results obtained on the physics of electrolyte gated organic field effect transistors (EGOFETs) are discussed.