Controlled
droplet manipulation by light has tremendous technological
potential. We report here a method based on photothermally induced
pyroelectric effects that enables manipulation and maneuvering of
a water droplet on a superhydrophobic surface fabricated on lithium
tantalite (LiTaO3). In particular, we demonstrate that
the pyroelectric charge distribution has an essential role in this
process. Evenly distributed charges promote a rapid hydrophobic to
hydrophilic transition featuring a very large water contact angle
(WCA) change of ∼76.5° in air. This process becomes fully
reversible in silicone oil. In contrast, the localized charge distribution
induced by guided laser illumination leads to very different and versatile
functionalities, including droplet shape control and motion manipulation.
The influence of a saline solution is also investigated and compared
to the deionized water droplet. The focusing effect of the water droplet,
a phenomenon that widely exists in nature, is particularly of interest.
Simple tuning of the laser incident angle results in droplet deformation,
jetting, splitting, and guided motion. Potential applications, such
as droplet pinning and transfer, are presented. This approach offers
a wide range of versatile functionalities and ready controllability,
including contactless, electrodeless, and precise spatial and fast
temporal control, with tremendous potential for applications requiring
remote droplet control.
Low-cost,
high-quality, and large-area superhydrophobic surfaces
are in high demand. This study demonstrates laser-engineered polydimethylsiloxane
(PDMS) as a platform for versatile and highly efficient water manipulation.
The fabrication process consists of two steps: patterning PDMS with
arrayed microlenses and laser pulse scanning. The obtained PDMS is
superhydrophobic and exhibits excellent chemical resistance, UV stability,
pressure robustness, and substantial mechanical durability. Notably,
there is no significant change in the water contact angles after storage
in air for 14 months. Microstructural analysis revealed that the sample
contained stable nanostructured inorganics such as crystalline silicon,
silicon carbide, and sp3-like carbon. The superhydrophobic
surface was demonstrated to have versatile and wide applications in
oil/water separation and water collection.
We have been focused on the exploitation of the limits of the performance of low cost sensors, used in an integrated way, both for classical and geodetic navigation. In this work, the navigation performance of the Android smartphone's IMU was assessed thoroughly. The raw IMU data from two smartphones, ''Xiaomi 8'' and ''Honor Play'' were recorded, using different sampling rates, and compared with the measurements, recorded simultaneously from higher grade IMU's. For assessing the navigation capabilities of the smartphones IMU sensors, two kinematic tests were designed. In these tests, the smartphones IMU data were processed using a 15-state Kalman Filter developed by our group, while the reference IMU data were processed using a commercial software. The details of the comparisons between the positioning, velocity and attitude solutions are discussed. The results show that the navigation solutions of both smartphones are quite close to that of the reference IMUs', showing differences of around 0.2 m in positioning, 0.3 m/s in velocity, and 1 • in roll and pitch. The quality of the yaw estimation, with an accuracy of a few degrees, is clearly worse than that of the other attitude parameters. However, the results of the second test reveal that using a higher data rate setting for the IMU samplings, it is possible to improve the solution. The assessment study of the smartphone's IMUs performed in this work can be useful for the development of many different applications, including the exploitation for Autonomous Vehicles, Intelligent Transport Systems, and Smart Cities.
Sodium-ion batteries (SIBs) are developed to address the serious concern about the limited resources of lithium. To achieve high energy density, anode materials with a large specific capacity and a low operation voltage are highly desirable. Herein, microsized particles of gray Sn (α-Sn) are explored as an anode material of SIBs for the first time. The distinct structure of α-Sn endows it the reduced volume change, the improved interaction with polymer binders and the in situ formation of amorphous Sn, as supported by in situ XRD, TEM and DFT calculations. Therefore, α-Sn exhibits an excellent electrochemical performance, much better than β-Sn widely used before. Even microsized particles of α-Sn without any treatments deliver a capacity of ∼451 mAh g −1 after 3500 cycles at 2 A g −1 or ∼464 mAh g −1 at 4 A g −1 in a rate test. The results indicate the promising potential of α-Sn in SIBs.
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