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Flexible capacitive pressure sensors with a simple structure and low power consumption are attracting attention, owing to their wide range of applications in wearable electronic devices. However, it is difficult to manufacture pressure sensors with high sensitivity, wide detection range, and low detection limits. We developed a highly sensitive and flexible capacitive pressure sensor based on the porous Ecoflex, which has an aligned airgap structure and can be manufactured by simply using a mold and a micro-needle. The existence of precisely aligned airgap structures significantly improved the sensor sensitivity compared to other dielectric structures without airgaps. The proposed capacitive pressure sensor with an alignment airgap structure supports a wide range of working pressures (20–100 kPa), quick response time (≈100 ms), high operational stability, and low-pressure detection limit (20 Pa). Moreover, we also studied the application of pulse wave monitoring in wearable sensors, exhibiting excellent performance in wearable devices that detect pulse waves before and after exercise. The proposed pressure sensor is applicable in electronic skin and wearable medical assistive devices owing to its excellent functional features. [ABSTRACT FROM AUTHOR]

Electrohydrodynamic (EHD) printing was employed here to fabricate conductive micro patterns for printed electronic devices. EHD printing offers fine pattern fabrication through additive manufacturing that has several advantages when compared to conventional lithographic techniques. One of the major advantages of additive manufacturing is its ability to print on already fabricated devices for the purpose of alteration or repair. However, printing of micro patterns on a fabricated MEMS device is a tedious task due to the electrostatically induced disturbances in cone jet and the formation of satellite droplets. In this study, a modified EHD printing technique called drop on demand (DOD) process was used to print silver micro patterns on a MEMS device with high accuracy. The focus here was to optimize the technique and parameters, and modify the system hardware to enable patterning on an un-treated device surface. Parameters like supply voltage, waveform shape and frequency, pneumatic pressure, and ink flow rate have been studied and optimized to achieve repeatable and stable conductive patterns up to 3 μm. The modified EHD-DOD system also eliminates the problem of static surface charges by using low voltage thus enabling printing of highly repeatable sub-10 μm conductive patterns well suitable for MEMS repair. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid nanocomposites are an attractive choice for various electronic device applications. Owing to the unique characteristics of hybrid nanocomposites, we have explored the memory effect in a device, based on a 2D material: boron nitride (BN) and a polymer, polyvinyl alcohol (PVOH). This memory device has been fabricated on a flexible ITO coated PET substrate by using an all printed approach including electrohydrodynamic atomization (EHDA) and reciprocating head (RPC). The fabricated device displayed nonvolatile, rewritable and characteristic bipolar resistive switching at a low current compliance and small operating voltage. The conduction mechanism was deduced to be conductive filamentary and verified by the effect of temperature and device size on switching characteristics. Raman, FTIR and UV/Vis spectroscopies were employed in studying the optical properties of as-deposited hBN/PVOH thin films. The morphological characteristics were analyzed by FESEM and AFM techniques. A bendability test at various bending diameters (50–4 mm) for 1500 cycles was carried out to show the mechanical robustness of the fabricated device. The remarkably stable and repeatable results of electrical and mechanical characterization make this hybrid nanocomposite a potential candidate for future flexible, robust and low power nonvolatile memory devices. [ABSTRACT FROM AUTHOR]

Choi, T.J.; Choi, J.Y.; Park, J.Y., and Yang, Y.J., 2020. Long-term temporal and spatial morphological variability of a nourished beach using the EOF analysis. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 428–432. Coconut Creek (Florida), ISSN 0749-0208. Byeonsan Beach located at the west coast of Korea has been eroded seriously since 2006 after the construction of the Saemangeum dike. For this reason beach nourishment has been conducted from 2011 until 2017, and the result was successful by turning the beach in erosional phase of -4.1 cm/yr (2006 to 2010) into depositional condition of +2.0 cm/yr (2011 to 2017). Based on the EOF analysis of sixty-nine beach surveys during 13-year period from 2006 to 2019, the first four modes accounted for nearly 83% of total variability, leading to the interpretations of beach-nourishment effect, artificial construction, the influence of beach ridges migration, and irrigation-channel effect, respectively. [ABSTRACT FROM AUTHOR]