Current Issue : April-June Volume : 2022 Issue Number : 2 Articles : 5 Articles
Due to their uniquely high surface-to-volume ratio, nanofibers are a desired material for various technical applications. However, this surface-to-volume ratio also makes processing difficult as van der Waals forces cause nanofibers to adhere to virtually any surface. The cribellate spider Uloborus plumipes represents a biomimetic paragon for this problem: these spiders integrate thousands of nanofibers into their adhesive capture threads. A comb on their hindmost legs, termed calamistrum, enables the spiders to process the nanofibers without adhering to them. This anti-adhesion is due to a rippled nanotopography on the calamistrum. Via laser-induced periodic surface structures (LIPSS), these nanostructures can be recreated on artificial surfaces, mimicking the non-stickiness of the calamistrum. In order to advance the technical implementation of these biomimetic structured foils, we investigated how climatic conditions influence the anti-adhesive performance of our surfaces. Although anti-adhesion worked well at low and high humidity, technical implementations should nevertheless be air-conditioned to regulate temperature: we observed no pronounced anti-adhesive effect at temperatures above 30 C. This alteration between anti-adhesion and adhesion could be deployed as a temperature-sensitive switch, allowing to swap between sticking and not sticking to nanofibers. This would make handling even easier....
In this study, a bionic nonsmooth drag-reducing surface design method was proposed; a mathematical model was developed to obtain the relationship between the altitude of the nonsmooth drag-reducing surface bulges and the spacing of two bulges, as well as the speed of movement, based on which two subsoiler shovel tips were designed and verified on field experiments. The mechanism of nonsmooth surface drag reduction in soil was analyzed, inspired by the efficient digging patterns of antlions. The nonsmooth surface morphology of the antlion was acquired by scanning electron microscopy, and a movement model of the nonsmooth surface in soil was developed, deriving that the altitude of the nonsmooth drag-reducing surface bulge is proportional to the square of the distance between two bulges and inversely proportional to the square of the movement speed. A flat subsoiler shovel tip and a curved tip were designed by applying this model, and the smooth subsoiler shovel tips and the pangolin scale bionic tips were used as controls, respectively. The effect of the model-designed subsoilers on drag reduction was verified by subsoiling experiments in the field. The results showed that the resistance of the model-designed curved subsoiler was the lowest, the resistance of the pangolin scale bionic subsoiler was moderate, and the resistance of the smooth surface subsoiler was the highest; the resistance of the curved subsoiler was less than the flat subsoilers; the resistance reduction rate of the model-designed curved subsoiler was 24.6% to 33.7% at different depths. The nonsmooth drag reduction model established in this study can be applied not only to the design of subsoilers but also to the design of nonsmooth drag reduction surfaces of other soil contacting parts....
For a long time, underwater robot has been used as a scientific research tool and a teaching platform, but the real application products have not been well explored. The successful case of UAV gives underwater robot a higher expectation. How to apply underwater robot and enter the market has become a hot spot of underwater robot research at present. This paper mainly introduces a bionic fish-shaped robot, redefines underwater robot with innovative thinking, determines product functions from the perspective of the market, and develops product functions and designs and realizes the structure of each part according to the existing scientific research experience. Main innovation points of this design are to adopt the way of the hybrid propulsion for underwater robot movement, through the form of a hybrid propulsion and long range and the contradiction between the rapid maneuver, at the same time of umbilical cord cable, using float design improvement, and through the highly integrated ground station for the system operation control....
Embedding nanostructures in organic solar cells (OSCs) is awell-known method to improve the absorption efficiency of the device by introducing the plasma resonance and scattering effects without increasing the active layer thickness. The introduction of nanostructures imposes greater demands on the optical analysis method for OSCs. In this paper, the generalized rigorous coupledwave analysis (GRCWA) is presented to analyze and optimize the performance of coherent-incoherent hybrid organic solar cells (OSCs) with nanostructures. Considering the multiple reflections of light scattered within the glass substrate by the device, the correction vector g is derived, then the modified expressions for the field and absorption distribution in OSCs are provided. The proposed method is validated by comparing the simulated results of various structures with results obtained by the generalized transfer matrix method (GTMM) and the “equispaced thickness method” (ETM). The results demonstrate that the proposed method can reduce the number of simulations by at least half compared to the ETM while maintaining accuracy. With the proposed method, we discussed the device performance depending on the geometrical parameters of nanostructures, and the optimization and analysis are accomplished for single and tandem OSCs. After optimization based on the proposed method, the performance of OSCs are significantly improved, which further demonstrates the practicality of the method....
Multifunctional biomaterials can pave a way to novel types of micro- and nanoelectromechanical systems providing benefits in mimicking of biological functions in implantable, wearable structures. The production of biocomposites that hold both superior electrical and mechanical properties is still a challenging task. In this study, we aim to fabricate 3D printed hydrogel from a biocomposite of bovine serum albumin with graphene oxide (BSA@GO) using femtosecond laser processing. We have developed the method for functional BSA@GO composite nanostructuring based on both two-photon polymerization of nanofilaments and direct laser writing. The atomicforce microscopy was used to probe local electrical and mechanical properties of hydrogel BSA@GO nanowires. The improved local mechanical properties demonstrate synergistic effect in interaction of femtosecond laser pulses and novel composite structure....
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