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The growing need for alternative sources to power Internet of Things and autonomous devices has led to many energy harvesting solutions from ambient energy sources. Use of batteries requires complementary energy source for extending the lifetime of the device. In recent times, triboelectric nanogenerators have gained significant attention in charging applications through ambient energy harvesting field due to their simplicity, efficiency and adaptability to many device configurations in nature. It is deemed to sustainably address power for autonomous smart applications in various environmental conditions. In this work, a state-of-the-art triboelectric nanogenerator based on wind actuated venturi design system is demonstrated in sync with the smart system evolution for powering various sensor nodal network. Using natural wind, the 3D printed wind actuated venturi triboelectric energy harvester converts ambient mechanical energy into electricity. This simple and compact device produces an optimum average power of 1.5 mW and produces a maximum output power density of 2850 mW.m-2 (peak power output of 4.5 mW), which is much higher than the existing reports that use larger surface area at higher wind velocity. Extensive material testing and future implementation in an array of applications aids for environment friendly energy production and increase the role of triboelectric nanogenerator in autonomous applications.

A soft, conformable, biocompatible strain sensor based on ultra-thin stretchable electronics is reported. The sensor comprises gold thin films patterned on a 50 μm thick polyurethane substrate to produce resistive-based strain sensors for monitoring bladder stretch. The sensor responds linearly as a function of strain from 0 to 50%, with an increasing sensitivity as a function of sensor length. The sensor displays good stability with very little hysteresis when it is subjected to cycling between 0 and a maximum strain of 50%, with the largest deviation between 0 and 50% strain of ∼19% after 100 cycles attributed to the sensor with the longest length (6 mm) because it physically stretches by a greater distance than sensors with a shorter length. “Breaking” tests on the sensor reveal that shorter sensors can withstand higher maximum strains than longer sensors. A biocompatible hydrogel adhesive is used to attach sensors in vitro to the outside wall of a pig’s bladder, and sensor performance is studied with respect to repeated bladder filling and emptying to investigate stretch changes. By monitoring bladder stretch and thus volume noninvasively, the sensor provides a route for developing new treatment options for various urological conditions.

The condition for incorporating simple gases with H2O to form clathrate hydrates in protosolar nebula is a subject of topical interest. Methane and carbon dioxide clathrate hydrates have been speculated to exist in outer solar system bodies, but they have eluded direct detection so far. We have constructed a low-temperature and high-vacuum system to prepare and study clathrate hydrates by in situ synchrotron X-ray diffraction experiments. Upon heating, we found clathrate hydrates can be obtained from the codeposition of methane or carbon dioxide with water outside the equilibrium thermodynamic stability region under high vacuum. We suggested that the hydrate formation is assisted by the phase transformations in the ice, which provide the necessary activation energy to increase the mobility of the guest and water molecules. The results provide a new perspective on how “metastable” gas hydrate can be formed.

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