Nowadays, oily wastewater and spilled oil have caused great threats on both ecosystem and human life. To address these severe problems, considerable efforts have been possessed on developing novel oil/water separation materials. The porous oil-absorbent materials, especially the porous polydimethylsiloxane (PDMS) with excellent properties of easy fabrication and inherent hydrophobicity, have attracted tremendous attentions from worldwide. The conventional methods using salt or sugar as sacrificial template and water as solvent have been widely adopted to fabricate the porous PDMS sponge. Due to the inherent hydrophobicity of PDMS, the solvent of water hardly penetrates into the inside of PDMS, which results in the difficult and incomplete remove of the hard template. In this contribution, the 3D interconnected porous PDMS sponge is facilely prepared by utilizing a modified technique with the citric acid monohydrate as hard template and ethanol as solvent. The proposed approach is capable of removing the hard template efficiently and thoroughly, which demonstrates promising utilizations in practical applications.
Flexible pressure sensors attract wide attentions in recent years for their significant applications in wearable electronics and health monitoring. It is strongly desired that a pressure sensor possesses both low detection limit and wide measuring capability, covering a broad pressure range from Pa to hundred kPa, to meet diverse demands in different applications. This paper proposes a novel flexible pressure sensor based on thermosensation, using a multilayered and graded-porosity polydimethylsiloxane/silver nanoparticle sponge as piezo-thermic transduction. The sensor exhibits a high sensitivity, a low detection limit of 4.1 Pa, and a wide measuring range up to 200 kPa, which leads to a high range-to-limit ratio of about 50 000. The pressure sensor is monolithically integrated with a temperature sensor and dissolves temperature-compensation. The unique combination of properties makes it feasible to monitor various human signals from subtle wrist pulse to finger tapping pressure and foot stepping pressure by a single device, which shows competent capabilities for multifarious applications in wearable electronics and health monitoring.
Xi Guangshuai,Zhang Dongzhi,Tang Mingcong,Zhang Hao,Sun Yuehang,Zhang Yubiao,Cai Haolin,Xia Hui,Zhou Dandi
In recent years, multi-modal flexible tactile sensors have become an important direction in the development of electronic skin because of their excellent sensitivity, flexibility and wearable properties. In this work, a humidity-pressure multi-modal flexible sensor based on polypyrrole (PPy)/Ti 3 C 2 T x sensitive film packaged with porous polydimethylsiloxane (PDMS) is investigated by combining the sensitive structure generation mechanism of in situ polymerization to achieve the simultaneous detection of humidity and pressure, which has a sensitivity of 89,113.4 Ω/% RH in a large humidity range of 0%–97% RH, and response/recovery time of 2.5/1.9 s. The tactile pressure sensing has a high sensitivity, a fast response of 67/52 ms, and a wide detection limit. The device also has excellent performance in terms of stability and repeatability, making it promising for respiratory pattern and motion detection. This work provides a new solution to address the construction of multi-modal tactile sensors with potential applications in the fields of medical health, epidemic prevention.
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