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Abstract Printed organic sensors are of significant importance owing to their simplicity, low cost, easy fabrication and solution processability. However, organic sensors often suffer from the drawback of performance degradation when exposed to ambient environment. In this study, polyvinyl alcohol (PVA) is used as the functional layer of a temperature sensor and is encapsulated by aluminum oxide (Al 2 O 3) deposited through spatial atmospheric atomic layer deposition system (SAALD). The encapsulating layer of Al 2 O 3 was pure, atomically thin and highly reliable. Fabricated organic temperature sensor is based on a conductive and uniform interdigitated pattern deposited on a flexible polyethylene naphthalate substrate through advanced printing technology of reverse offset. Thin film of PVA is used as the temperature sensitive functional layer deposited through electrohydrodynamic atomization followed by Al 2 O 3 encapsulation. The developed sensors were tested in the temperature range of 25 °C to 90 °C with relative humidity reaching up to 75% relative humidity. The obtained results exhibited that Al 2 O 3 encapsulation deposited through SAALD significantly enhanced the linearity, repeatability, endurance (50 cycles), retention (2 months) and lifetime of PVA based temperature sensor as compared with the non-encapsulated sensor hence, protecting the organic device from performance degradation. Highlights • Lifetime of organic temperature sensor has been enhanced through encapsulation. • Electrical, mechanical, chemical, and morphological characterizations are included. • The device is encapsulated with Al 2 O 3 thin film deposited through SAALD system. • Encapsulated sensor displayed better results than non-encapsulated sensor. • The obtained results were highly stable and reproducible. [ABSTRACT FROM AUTHOR]

Functional thin film of strontium titanate/polyvinyl alcohol (SrTiO 3 -PVA) hybrid nanocomposite was sandwiched between silver (Ag) electrodes for the application of resistive random access memory (RRAM). Bottom Ag electrodes were patterned using high resolution reverse offset printing system while the hybrid composite thin film and the top Ag electrode were deposited through electro-hydrodynamic (EHD) atomization and EHD patterning respectively. RRAM behavior of SrTiO 3 memory device has not been reported on a flexible substrate due to its brittle nature therefore, in this study we have successfully evaluated its mechanical robustness by forming its nanocomposite with highly flexible PVA polymer. The fabricated device showed bipolar, rewritable and nonvolatile memory behavior at low operating voltage. The bistable resistive switching behavior had off/on ratio of ~30, retention time of 8.64 × 104 s and electrical endurance of 500 operating cycles. The device illustrated mechanical robustness when subjected to 500 bend cycles and varying bending diameters. Image 100539 • A flexible resistive memory device was fabricated using hybrid composite thin film. • SrTiO 3 +PVA thin film was deposited using EHDA spray deposition technique. • All-printed memory device exhibited improved electrical and mechanical endurance. • It showed bistable, rewritable, nonvolatile memory behavior at low working voltage. • The device showed excellent mechanical robustness when tested for 500 bend cycles. [ABSTRACT FROM AUTHOR]

• A piezocapacitive biodegradable pressure sensor has been fabricated. • Device targets low pressure measurements in tactile range of 0 < P < 5 kPa. • Nanofibrous PLGA-PCL membrane has been used as elastomeric dielectric. • It was used for wrist pulse monitoring and pressure mapping array applications. • 7 days of degradation caused a 19.5% decrease in sensitivity in low pressure range. High performance biodegradable electronic devices are becoming popular due to their enormous applications as biomedical implants or short term communication devices. They are biocompatible and eco-friendly. For example wearable or implantable biodegradable pressure sensors are very useful for cardiovascular or blood flow monitoring. But unfortunately very few previous researches have focused on developing biodegradable pressure sensors. Here we propose a composite of Polylactic-co-glycolic acid (PLGA) and Polycaprolactone (PCL) for biodegradable piezo-capacitive pressure sensor fabrication for low pressure measurement in tactile ranges of (0 < P < 5 kPa). An electrospun PLGA-PCL composite membrane has been used as elastomeric dielectric sandwiched between two biodegradable iron-zinc (Fe-Zn) bilayer electrodes, deposited on degradable Polyvinyl alcohol (PVA) substrate using electron beam deposition, and encapsulated in PLGA thin films for device fabrication. PLGA-PCL nanofibrous dielectric membrane is highly compressible and porous having tunable mechanical as well as dielectric properties and has been reported first ever for biodegradable pressure sensor application. The sensitivity of the sensor was found to be 0.863 ± 0.025 kPa−1 in the low pressure region (0 < P ≤ 1.86 kPa) which is quite high as compared to previous literature on biodegradable sensors so far while it adapted to a value of 0.062 ± 0.005 kPa−1 for high pressure region (1.86 kPa < P ≤ 4.6 kPa). The lowest detected value was 1.24 Pa (at 10mgf). Sensor showed good average response and recovery times of 251 ms and 170 ms respectively. In vitro degradation studies of the sensor were performed in PBS solution and sensor lost 60% of its initial weight during first two weeks of degradation and continued to degrade even after that. After one week of incubation sensor showed a 19.5% decrease in low pressure measurement range while there was no significant difference in upper detection range. It has been used to measure the arterial pulse wave on wrist and a 4 × 4 pressure sensor array was made to demonstrate its use in mapping different pressure points. [ABSTRACT FROM AUTHOR]