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The development of multifunctional organic materials represents a vibrant area of research, with applications spanning from biosensing to drug delivery. This study shows the development of a multifunctional bioelectronic device suitable for prolonged temperature monitoring and drug delivery applications. The device relies on a conducting and thermo‐responsive hydrogel made of poly(3,4‐ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) and poly(N‐isopropylacrylamide) (PNIPAM). This multifunctional hydrogel is 4D printable by Digital Light Processing (DLP) method and exhibits optimal biocompatibility. The hydrogel features a low critical solution temperature (LCST) ≈35 °C, above which its resistance changes dramatically due to the shrinkage it undergoes with temperature. The integration of PNIPAM/PEDOT hydrogel into an organic electrochemical transistor (OECT) as the gate electrode allows to generate a miniaturized bioelectronic device with a reversible response to temperature variations between 25 to 45 °C, along with high sensitivity of 0.05 °C−1. Furthermore, the PNIPAM/PEDOT hydrogel demonstrates its utility in drug delivery, achieving an Insulin‐FITC release rate of 82 ± 4% at 37 °C, mimicking human body conditions. The hydrogel's functionality to store and release the insulin does not compromise its thermo‐responsivity and the overall performance of the OECT. This multifunctional OECT opens new avenues for the development of customizable and personalized sensing and drug‐delivery systems. [ABSTRACT FROM AUTHOR]

The ability to operate in aqueous environments makes poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, based organic electrochemical transistors (OECTs) excellent candidates for a variety of biological applications. Current research in PEDOT:PSS based OECTs is primarily focused on improving the conductivity of PEDOT:PSS film to achieve high transconductance (gm). The improved conductivity and electronic transport are attributed to the formation of enlarged PEDOT‐rich domains and shorter PEDOT stacking, but such a change in morphology sacrifices the ionic transport and, therefore, the doping/de‐doping process. Additionally, little is known about the effect of such morphology changes on the gate bias that makes the maximum gm (VGPeak), threshold voltage (VT), and transient behavior of PEDOT:PSS based OECTs. Here, the molecular packing and nanostructure of PEDOT:PSS films are tuned using ionic liquids as additives, namely, 1‐Ethyl‐3‐methylimidazolium (EMIM) as cation and anions of chloride (Cl), trifluoromethanesulfonate (OTF), bis(trifluoromethylsulfonyl)imide (TFSI), and tricyanomethanide (TCM). It is demonstrated that an optimal morphology is realized using EMIM OTF ionic liquids that generate smaller fibril‐like PEDOT‐rich domains with relatively loose structures. Such optimal morphology improves ion accessibility, lowering the gate bias required to completely de‐dope the channel, and thus enabling to achieve high transconductance, fast transient response, and at lower gate bias window simultaneously. [ABSTRACT FROM AUTHOR]

Ultra‐lightweight solar cells have attracted enormous attention due to their ultra‐conformability, flexibility, and compatibility with applications including electronic skin or miniaturized electronics for biological applications. With the latest advancements in printing technologies, printing ultrathin electronics is becoming now a reality. This work offers an easy path to fabricate indium tin oxide (ITO)‐free ultra‐lightweight organic solar cells through inkjet‐printing while preserving high efficiencies. A method consisting of the modification of a poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) ink with a methoxysilane‐based cross‐linker (3‐glycidyloxypropyl)trimethoxysilane (GOPS)) is presented to chemically modify the structure of the electrode layer. Combined with plasma and solvent post‐treatments, this approach prevents shunts and ensures precise patterning of solar cells. By using poly(3‐hexylthiophene) along rhodanine‐benzothiadiazole‐coupled indacenodithiophene (P3HT:O‐IDTBR), the power conversion efficiency (PCE) of the fully printed solar cells is boosted up to 4.73% and fill factors approaching 65%. All inkjet‐printed ultrathin solar cells on a 1.7 µm thick biocompatible parylene substrate are fabricated with PCE reaching up to 3.6% and high power‐per‐weight values of 6.3 W g−1. After encapsulation, the cells retain their performance after being exposed for 6 h to aqueous environments such as water, seawater, or phosphate buffered saline, paving the way for their integration in more complex circuits for biological systems. [ABSTRACT FROM AUTHOR]

Lipid bilayers are widely employed as a model system to investigate interactions between cells and their environment. Supported lipid bilayers (SLB) with integrated transmembrane proteins are emerging as a preferred platform for sensing applications. Challenges lie in the generation of SLB on surfaces which allow transduction of signals for characterization of lipid bilayer and incorporated transmembrane proteins. For the first time, the formation of SLBs is shown on films of the conducting polymer, poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS), using traditional methods for characterizing lipid bilayer quality and function (QCM-D, FRAP) combined with impedance spectroscopy. Further, partial formation of SLBs on PEDOT:PSS based organic electrochemical transistors (OECTs) is successfully demonstrated, as well as the ability to integrate and sense the ion pore α-hemolysin, confirming the sensitivity of the OECT as a transducer of biological membrane function. This work represents a highly promising first step toward the use of such OECTs for functional readout of transmembrane proteins in their native environment. [ABSTRACT FROM AUTHOR]

ABSTRACT Recent applications of organic electrochemical transistors (OECTs) in bioelectronics motivate the search for new materials with mixed electronic and ionic conductivity. We investigate the characteristics of a series of poly(3,4-ethylenedioxythiophene) (PEDOT)-based materials with a new class of anionic polyelectrolytes used as dopants and stabilizers, replacing the traditionally used poly(styrene sulfonate) (PSS). We show that the backbone of the polyanion plays a major role in determining device performance, while its molecular weight and the counter ion used during PEDOT synthesis play a less important role. We find that transconductance increases with the degree of swelling of the film, consistent with enhanced ion transport. Finally, we identify a polymer that offers performance close to the state-of-the-art. This work highlights the importance of the polyanion phase as a means to control OECT performance. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 147-151 [ABSTRACT FROM AUTHOR]

In article number 1800928, Shofarul Wustoni, Sahika Inal and co‐workers demonstrate an all‐polymer based, non‐enzymatic, glucose sensitive electroactive gel. The conducting gel, fabricated via a single#x02010;step electropolymerization, is employed either as an amperometric sensor or as a micrometer‐scale gate electrode of an organic electrochemical transistor. At both configurations, this hybrid material offers selective and sensitive sensing performance at low operation voltages in complex blood‐like medium. The cover was designed by Heno Hwang, scientific illustrator, King Abdullah University of Science and Technology. [ABSTRACT FROM AUTHOR]

Current assays for glucose monitoring rely predominantly on glucose oxidation‐catalyzing enzymes because of the high specificity of enzyme–substrate interactions. Enzymes are however expensive, suffer from instability during fabrication, operation, and storage, and necessitate complex procedures for integration with transducer materials. These challenges, rendering the enzyme‐based sensors disadvantageous for routine glucose monitoring, can be overcome by nonenzymatic sensors. Here, for the enzyme‐free detection of glucose, an electroactive gel is developed via one‐pot polymerization. The functional material is a hybrid of the conducting polymer poly(3,4‐ethylenedioxythiophene):polystyrenesulfonate and a polyacrylamide gel functionalized with phenylboronic acid. As an electrode, the gel exhibits a specific current response to glucose within the standard concentration range measured in the complex blood‐like medium. When integrated as the lateral, micrometer‐scale gate electrode of an organic electrochemical transistor (OECT), the channel current is proven to be sensitive to the presence of glucose in the measurement solution. The advantage of the OECT‐based sensor compared to the amperometric electrode is its miniaturized form, amplified input signal as well the elimination of a reference electrode. Adaptable to different geometries, this conducting gel exhibits multifunctionality within its soft, gel‐like architecture, that is, mixed ionic and electronic conductivity and glucose‐specific electrical response. This work demonstrates, for the first time, an all‐polymer based, nonenzymatic, glucose‐sensitive electroactive material. The conducting gel is fabricated via a single‐step electropolymerization and employed either as an amperometric sensor or as a micrometer‐scale gate electrode of an organic electrochemical transistor. At both configurations, this hybrid material offers selective and sensitive electrical sensing performance at low operation voltages. [ABSTRACT FROM AUTHOR]

• The preparation of fully inkjet printed PEDOT:PSS/ZnO/Nafion sensor on commercial printing paper.. • A paper based electrochemical sensor for hydrazine sensing with a good selectivity and reproducibility. • Sensitivity comparison of PEDOT:PSS/Nafion and PEDOT:PSS/ZnO/Nafion sensors. • Characterization of PEDOT:PSS and ZnO through SEM, XPS and AFM. • Excellent detection in real samples with a recovery of 98.7–104.2 %. Hydrazine is widely used in industries as a precursor for blowing agents, pharmaceuticals, and pesticides. It is a highly toxic compound; therefore, it is of paramount interest to develop new analytical methods for the detection and control of hydrazine exposure. In this work, we describe the fabrication of an all inkjet-printed paper sensor composed of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) electrode functionalized with zinc oxide (ZnO) and encapsulated in a Nafion matrix for the amperometric determination of low concentrations of hydrazine. The electrochemical properties of the fully inkjet-printed PEDOT:PSS/Nafion and PEDOT:PSS/ZnO/Nafion sensors are compared in the presence and absence of different concentrations of hydrazine. The stability and sensitivity of these electrodes are significantly enhanced after modification with ZnO particles. The layer-by-layer deposition of the materials on the electrode surface is characterized by SEM, XRD, and AFM. The printed sensor exhibits a linear response in the 10–500 μM hydrazine concentration range and a ∼5 μM detection limit (at S/N = 3). The electrochemical sensitivity is 0.14 μA μM−1 cm−2, and the best working voltage is 0.5 V. The developed sensor was applied successfully for the determination of hydrazine content in tap, sea, and mineral water samples validating the accuracy of this sensor. [ABSTRACT FROM AUTHOR]