Ionic polymer materials can generate an electrical potential from ion migration under an external force. For traditional ionic polymer metal composite sensors, the output voltage is very small (a few millivolts), and the fabrication process is complex and time-consuming. This letter presents an ionic polymer based network of pressure sensors which is easily and quickly constructed, and which can generate high voltage. A 3 × 3 sensor array was prepared by casting Nafion solution directly over copper wires. Under applied pressure, two different levels of voltage response were observed among the nine nodes in the array. For the group producing the higher level, peak voltages reached as high as 25 mV. Computational stress analysis revealed the physical origin of the different responses. High voltages resulting from the stress concentration and asymmetric structure can be further utilized to modify subsequent designs to improve the performance of similar sensors.

Three isolates (HK1, GSDM02, and GSDM15) were tested for effectiveness in biodegradation of plastic films. Isolates were screened by plate on carbon-free medium and by using the clear-zone formation test. Their biodegradation ability was analyzed based on: film weight reduction, pH change of the fluid medium, a soil microbial biomass carbon test, scanning electron microscopy (SEM), and Fourier transform infrared spectrometry (FTIR). Polyvinyl alcohol (PVA) clear-zone and film weight reduction results revealed that the strain with a bigger clear-zone had a better biodegradation effect, that PVA can be evenly distributed in the medium, and that PVA can be a substitution for polyethylene in screening the biodegradation of strains. SEM and FTIR revealed that HK1 can tear the film apart and make surface chemical changes within 30 days. HK1 exhibited a better biodegradation effect in all tests, indicating its potential for helping solve the plastic pollution problems.

Acoustic focusing has been widely applied in biological and industrial fields. In this work, a coding acoustic metasurface consisting of two kinds of hexagonal coding bits is designed. Using the metasurface, acoustic focusing can be implemented in three-dimensional space. Besides, by altering the coding sequence, the focal length can be manipulated flexibly to satisfy the practical demands. Furthermore, bifocal focusing, which has a great potential in multiplane imaging, can be realized by properly arranging the coding sequence. Our works broaden the prospects of the coding metasurfaces and have promising applications in the areas of biomedical therapy and imaging.

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