We report evaporation of ethanol/water mixture droplets on both pillar-arrayed and micro-holed polydimethylsiloxane (PDMS) surfaces. Analysis of wettability shows that (i) when the pillar-to-pillar spacing is 5 μm, the pillar-arrayed PDMS surfaces are Cassie-Baxter-wetted; (ii) when the pillar-to-pillar spacing is 20 or 50 μm, part of each pillar-arrayed surface is Cassie-Baxter-wetted while the other part Wenzel-wetted; (iii) all micro-holed PDMS surfaces are Cassie-Baxter-wetted; (iv) the advancing and receding contact angles increase with the increase of the pillar-to-pillar spacing, while they decrease with the increase of the hole-to-hole spacing. The investigation on evaporation of mixture droplets demonstrates that (i) evaporation on pillar-arrayed PDMS first proceeds with constant contact radius mode (CCR) due to the strong adhesion between the surface and the droplet; (ii) on micro-holed surfaces CCR stage is also observed for the surface with the hole-to-hole spacing of 5 μm, while it is not found at high ethanol concentration for surfaces with the hole-to-hole spacings of 20 μm and 50 μm, which is attributed to the weak adhesion between the micro-holed surfaces and the droplet. Finally, the evolution of droplet volume and its two-third power are discussed.
Siyuan Huang,Qi Su,Xiaoqiang Hou,Kuankuan Han,Shufang Ma,Bingshe Xu,Yingjun Yang
High transmembrane delivery efficiency of nanoparticles has attracted substantial interest for biomedical applications. It has been proved that the desired physicochemical properties of nanoparticles were efficient for obtaining a high cellular uptake capacity. On the other hand, biophysical stimuli from in situ microenvironment were also indicated as another essential factor in the regulation of cellular uptake capacity. Unfortunately, the influence of colony morphology on cellular uptake capacity was rarely analyzed. In this study, micropatterned PDMS stencils containing circular holes of 800/1,200 μm in diameter were applied to control colonies’ size. The amino-modified nanoparticles were cocultured with micropatterned colonies to analyze the influence of colonies’ morphology on the cellular uptake capacity of nanoparticles. Consequently, more endocytosed nanoparticles in larger colonies were related with a bigger dose of nanoparticles within a larger area. Additionally, the high cell density decreased the membrane–nanoparticles’ contacting probability but enhanced clathrin-mediated endocytosis. With these contrary effects, the cells with medium cell density or located in the peripheral region of the micropatterned colonies showed a higher cellular uptake capacity of nanoparticles.
Yan Zhong,Jiaqi Wang,Lei Han,Shengping Dai,Hao Zhu,Jing Hua,Guanggui Cheng,Jianning Ding
Flexible pressure sensors have played an increasingly important role in the Internet of Things (IoT) and human–machine interaction (HMI) systems. However, it is in a desire to fabricate the sensor with high sensitivity and low power consumption . In this paper, we have developed a self-powered triboelectric pressure sensor based on chemically modified micropatterned PDMS . Different wire meshes serve as template to fabricate microstructures on the triboelectric layer. To enhance the triboelectric output performance, introducing functional groups to the surface of the triboelectric layer to expand triboelectric polarity difference. By virtue of the cooperative effect of enhanced contact area variations from the PDMS microstructure’s gradual deformation, the reduced dielectric thickness as well as the increased charge density from the extended triboelectric polarity difference originated from chemical modification, the self-powered triboelectric sensor displays a sensitivity of 44.31 V kPa −1 in the range of 0.006–2 kPa and 7.16 V kPa −1 in the range of 2–8.5 kPa. Additionally, the self-powered triboelectric sensor is efficient in human motions measurement. This work provides a route to fabricate high-performance pressure sensor with morphological and chemical modification on the triboelectric polymers.
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