We describe a process allowing the patterning of fully stretchable organic electrochemical transistors (OECTs). The device consists of an active stretchable area connected with stretchable metallic ...interconnections. The current literature does not provide a complete, simple and accurate process using the standard thin film microelectronic techniques allowing the creation of such sensors. An innovative patterning process based on the combination of laser ablation and thermal release tape ensures the fabrication of highly stretchable metallic lines - encapsulated in polydimethylsiloxane - from conventional aluminium tape. State-of-the-art stretchability up to 70% combined with ultra-low mOhms resistance is demonstrated. We present a photolithographic process to pattern the organic active area onto stretchable substrate. Finally the formulation of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) is tuned to achieve an OECT with a maximum stretchability of 38% while maintaining transconductance up to 0.35 mS and channel current as high as 0.2 mA.
Development of stretchable electronics has been driven by key applications such as electronics skin for robotic or prosthetic. Mimicking skin functionalities imposes at a minimal level: ...stretchability, pressure, and temperature sensing capabilities. While the research on pressure sensors for artificial skin is extensive, stretchable temperature sensors remain less explored. In this work, a stretchable temperature and infrared sensor has been developed on a polydimethylsiloxane substrate. The sensor is based on poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) as a pyroelectric material. This material is sandwiched between two electrodes. The first one consists of aluminium serpentines, covered by gold in order to get electrical contact and maximum stretchability. The second one is based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) that has shown good electrical compatibility with PVDF-TrFE and provides the stretchability of the top electrode. Without poling the PVDF-TrFE, sensor has shown a sensitivity of around 7 pF.°C
up to 35% strain without any change in its behaviour. Then, taking advantage on infrared absorption of PEDOT:PSS, a poled device has shown a pyroelectric peak of 13 mV to an infrared illumination of 5 mW at 830 nm. This stretchable device valuably allows an electronic skin (e-skin) use for contact and more importantly non-contact thermal sensing.
Eutectogels are a new class of soft ion conductive materials that are attracting attention as an alternative to conventional hydrogels and costly ionic liquid gels to build wearable sensors and ...bioelectrodes. Herein, the first example of mixed ionic and electronic conductive eutectogels showing high adhesion, flexibility, nonvolatility, and reversible low‐temperature gel transition for 3D printing manufacturing is reporting. The eutectogels consist of choline chloride/glycerol deep eutectic solvent, poly(3,4‐ethylenedioxythiophene): lignin sulfonate, and gelatin as the biocompatible polymer matrix. These soft materials are flexible and stretchable, show high ionic and electronic conductivities of 7.3 and 8.7 mS cm−1, respectively, and have high adhesion energy. Due to this unique combination of properties, they could be applied as strain sensors to precisely detect physical movements. Furthermore, these soft mixed ionic electronic conductors possess excellent capacity as conformal electrodes to record epidermal physiological signals, such as electrocardiograms and electromyograms, over a long time.
In this article, low‐cost adhesive eutectogels combining ionic and electronic conductivity are developed. The semi‐interpenetration of poly(3,4‐ethylenedioxythiophene): lignin sulfonate into a biopolymer matrix hosting glyceline deep eutectic solvent affords soft ionic materials with excellent mixed conductivity. The developed stretchable materials can be used to manufacture wearable sensors and bioelectrodes for long‐term cutaneous recordings.
Soft‐ionic materials with biocompatibility and 3D printability are needed to develop next‐generation devices to interface between electronic and biological signals. Herein, thermoreversible and ...biocompatible ionic liquid gels or iongels, which can be processed by direct ink writing are reported. The iongels are designed by taking advantage of polyvinyl alcohol/phenol interactions to gelify biocompatible cholinium carboxylate ionic liquids. The obtained iongels are stable, soft, and flexible materials (Young modulus between 14 and 70 kPa) with high ionic conductivity (1.8 × 10–2 S cm–1). Interestingly, they presented thermoreversible properties with gel–sol transitions ranging from 85 and 110 °C, which allows the iongel processing via direct ink writing 3D printing by material extrusion at temperatures over its transition. These 3D printable iongels are integrated into a variety of body sensors applications, namely pressure sensors, motion sensors and electrodes for electrophysiological recordings. The iongels are used as pressure sensors with a sensitivity of 0.1 kPa–1, ten times higher than that of others similar materials reported so far; showing its ability to detect human motion. Furthermore, the iongels showed excellent performance in electrodes for electrocardiography (ECG) recording, presenting good stability over time with electrocardiographic waves maintained their typical shape even after weeks.
Biocompatible iongels are designed by supramolecular polyvinyl alcohol/phenol interactions and using cholinium ionic liquids, which result in stable and flexible materials with high ionic conductivity. They are thermoreversible and it allows the iongels processing for 3D printing. The iongels show excellent performance as pressure sensors for detecting human motion and as electrodes for electrocardiography recording with good time stability.
Future drug discovery and toxicology testing could benefit significantly from more predictive and multi-parametric readouts from
models. Despite the recent advances in the field of microfluidics, and ...more recently organ-on-a-chip technology, there is still a high demand for real-time monitoring systems that can be readily embedded with microfluidics. In addition, multi-parametric monitoring is essential to improve the predictive quality of the data used to inform clinical studies that follow. Here we present a microfluidic platform integrated with in-line electronic sensors based on the organic electrochemical transistor. Our goals are two-fold, first to generate a platform to host cells in a more physiologically relevant environment (using physiologically relevant fluid shear stress (FSS)) and second to show efficient integration of multiple different methods for assessing cell morphology, differentiation, and integrity. These include optical imaging, impedance monitoring, metabolite sensing, and a wound-healing assay. We illustrate the versatility of this multi-parametric monitoring in giving us increased confidence to validate the improved differentiation of cells toward a physiological profile under FSS, thus yielding more accurate data when used to assess the effect of drugs or toxins. Overall, this platform will enable high-content screening for
drug discovery and toxicology testing and bridges the existing gap in the integration of in-line sensors in microfluidic devices.
Alteration in intestinal permeability is the main factor underlying the pathogenesis of many diseases affecting the gut, such as inflammatory bowel disease IBD. Characterization of molecules ...targeting the restoration of intestinal barrier integrity is therefore vital for the development of alternative therapies. The yeast Saccharomyces boulardii CNCM I-745 Sb, used to prevent and treat antibiotic-associated infectious and functional diarrhea, may have a beneficial effect in the treatment of IBD.
We analyzed the impact of Sb supernatant on tissue integrity and components of adherens junctions using cultured explants of colon from both IBD and healthy patients. To evaluate the pathways by which Sb regulates the expression of E-cadherin at the cell surface, we developed in vitro assays using human colonic cell lines, including cell aggregation, a calcium switch assay, real-time measurement of transepithelial electrical resistance TEER and pulse-chase experiments.
We showed that Sb supernatant treatment of colonic explants protects the epithelial morphology and maintains E-cadherin expression at the cell surface. In vitro experiments revealed that Sb supernatant enhances E-cadherin delivery to the cell surface by re-routing endocytosed E-cadherin back to the plasma membrane. This process, involving Rab11A-dependent recycling endosome, leads to restoration of enterocyte adherens junctions, in addition to the overall restoration and strengthening of intestinal barrier function.
These findings open new possibilities of discovering novel options for prevention and therapy of diseases that affect intestinal permeability.
Underwater recording remains a critical challenge in bioelectronics because traditional flexible electrodes can not fulfill essential requirements such as stability and steady conductivity in aquatic ...environments. Herein, we show the use of elastic gels made of hydrophobic natural eutectic solvents as water-resistant electrodes. These eutectogels are designed with tailorable mechanical properties via one-step photopolymerization of acrylic monomers in different eutectic mixtures composed of fatty acids and menthol. The low viscosity of the eutectics turns the formulations into suitable inks for 3D printing, allowing fast manufacturing of complex objects. Furthermore, the hydrophobic nature of the building blocks endows the eutectogels with excellent stability and low water uptake. The obtained flexible eutectogel electrodes can record real-time electromyography (EMG) signals with low interference in the air and underwater.
E‐cigarettes have been suggested as a potentially healthier alternative to cigarettes based on studies using cell viability, DNA damage, and transcriptional response assays. However, little is known ...about the effect of e‐cigarette aerosols on the integrity of the tracheal epithelium, specifically with respect to barrier resistance. This is partly due to the lack of methods for monitoring epithelia at the air–liquid interface (ALI), i.e., under physiological conditions. Here, it is shown that an organic electrochemical transistor can be adapted for the measurement of barrier resistance at the ALI. This technology enables accurate, continuous quantification of tracheal barrier integrity through the use of a conformable gate electrode placed on top of the cell‐secreted mucus, obviating the need for addition of culture medium or buffer as a conductance medium for rigid electrodes. This platform allows for the detection of a dose‐dependent, rapid decrease in barrier resistance of an in vitro model of human bronchial epithelium (MucilAir) after E‐cigarette aerosols exposure. The system represents a powerful tool to study tissue responses of the human airway epithelium to inhaled smoke. The same technology will have broad applications for toxicology studies on other tissues with ALI, including other airway tissues and skin.
Tracheal cells integrated into an organic electrochemical transistor can be monitored at the air–liquid interface (ALI). Continuous and quantitative monitoring of ALI barrier tissue resistance is performed by placing a flexible gate electrode in contact with the cell‐secreted mucus. The tissue blocks the gating of the transistor and barrier disruption during aerosol toxicity assays restoring the gating.
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