of the pressure sensor (iii). Sugar was added into the hole to create pores inside Ecoflex. Liquid Ecoflex was then poured into this part. By vacuuming the substrate, Ecoflex penetrated the regions in which sugar was deposited. After curing Ecoflex, the substrate was sonicated through ultrasonication to dissolve sugar (v). A solution of Super P carbon, fluoropolymer, PVDF, and N-methylpyrrolidone (NMP) was poured into the porous Ecoflex and penetrated this part (vi). This porous structure increased the resistance of the pressure sensing part. Finally, the column and row electrodes of the carbon paste were formed on the top and bottom sides of the substrate for the detection of the x and y strains. Acquisition of highly magnified images and analysis of molecules was performed using scanning electron microscopy (SEM) and with energy dispersive X-ray spectroscopy (EDS) of the carbon and fluorine elements (Fig. 2b-f). The resistance of the porous silicone pressure sensing element was different, depending on the material used in coating the surface of the porous silicone (Fig. 2g).

Highly deformable batteries that are flexible and stretchable are important for the next-generation wearable devices. Several studies have focused on the stable operation and life span of batteries. On the other hand, there has been less focus on the packaging of highly deformable batteries. In wearable devices, solid-state or pouch lithium-ion batteries (LIBs) packaged in aluminum (Al)-laminated films, which protect against moisture and gas permeation, are used. Stretchable elastomer materials are used as the packaging films of highly deformable batteries; however, they are extremely permeable to gas and moisture. Therefore, a packaging film that provides high deformability along with gas and moisture barrier functionalities is required for the stable operation of highly deformable batteries used in ambient conditions. In this study, a stretchable packaging film with high gas barrier functionality is developed successfully by coating a thin layer of liquid metal onto a gold (Au)-deposited thermoplastic polyurethane film using the layer-by-layer method. The film exhibits excellent oxygen gas impermeability under mechanical strain and extremely low moisture permeability. It shows high impermeability along with high mechanical robustness. Using the proposed stretchable gas barrier film, a highly deformable LIB is assembled, which offers reliable operation in air. The operation of the highly deformable battery is analyzed by powering LEDs under mechanical deformations in ambient conditions. The proposed stretchable packaging film can potentially be used for the development of packaging films in advanced wearable electronic devices.

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The gene encoding an esterase (HDE) was cloned from an oil-degrading bacterium, strain HD-1. HDE is a member of the hormone-sensitive lipase family and composed of 317 amino acid residues with a molecular weight of 33,633. The HDE-encoding gene was expressed in Escherichia coli, and the recombinant protein was purified and characterized. Amino acid sequence analysis indicated that the methionine residue was removed from its NH(2)-terminus. The good agreement of the molecular weights estimated by SDS-PAGE (35,000) and gel filtration (38,000) suggests that it acts in a monomeric form. HDE showed hydrolytic activity towards p-nitrophenyl esters of fatty acids with an acyl chain length of 2 to 14 and tributyrin, whereas it showed little hydrolytic activity towards p-nitrophenyl oleate (C(18)), tricaprylin and triolein. Determination of the kinetic parameters for the hydrolyses of the p-nitrophenyl substrates from C(2) to C(14) indicated that HDE shows a relatively broad substrate specificity. However, comparison of the k(cat)/K(m) values indicated that the C(10)-C(14) substrates are the most preferred ones. Such a preference for substrates with long acyl chains may be a characteristic of HDE.

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