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Small mobile robots with transformable wheels have recently emerged thanks to their increased mobility and maneuverability. When a high payload is applied to these robots, however, wheel transformation becomes difficult because they must directly overcome the payload’s weight. In this paper, we propose a wheel that can be transformed from its starting circular shape (radius, 56 mm) to a wheel with three legs (radius, 99 mm) under a high payload with low operating force. The key design principle of this wheel is to kinematically decoupled legs and passive locking. Its legs are kinematically decoupled but operated by a single air pump using a pneumatic channel connected to soft pneumatic actuators installed at each leg. Application of pressure causes the legs to behave like a coupled system through the pneumatic channel. With pressurization, the two legs that are not in contact with the ground easily emerge from body, and the leg in contact with the ground emerges once the wheel rotates. Once emerged, each leg is supported by a rigid pawl instead of by the soft pneumatic actuators. This setup enables the legs to be transformed independently with low air pressure, even under high payloads. It reduces system weight and the energy required to maintain the transformed shape. This legged wheel can overcome obstacles up to 2.9 times the radius of the wheel in its circular form, and wheel transformation can be accomplished with 85 kPa air pressure for payloads up to 1115 g.

A Gram reaction-negative, strictly aerobic, non-motile, translucent and rod-shaped bacterium (designated W1-2-4(T)) isolated from tap water was characterized by a polyphasic approach to clarify its taxonomic position. Strain W1-2-4(T) was observed to grow optimally at 25-30 °C and at pH 6.5 on nutrient agar. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain W1-2-4(T) belongs to the genus Sphingomonas and is most closely related to the Sphingomonas fennica K101(T) (95.3 % similarity). The G+C content of genomic DNA was 67.1 mol%. Chemotaxonomic data [major ubiquinone-Q-10, major polyamine-homospermidine, major fatty acids-summed feature 8 (comprising C18:1 ω7c/ω6c), C16:0 and C14:0 2OH] supported the affiliation of strain W1-2-4(T) to the genus Sphingomonas. Strain W1-2-4(T) could be differentiated genotypically and phenotypically from the recognized species of the genus Sphingomonas. The novel isolate therefore represents a novel species, for which the name Sphingomonas hankyongensis sp. nov. is proposed, with the type strain W1-2-4(T) (=KACC 18308(T) = LMG 28595(T)).

We propose a two-dimensional (2-D) in-plane micro-needle array with shaft sidewalls aligned parallel to the vertical (111) crystalline plane of (110) silicon. Six types of needle tips with various shapes and tapered angles were fabricated so as to maintain the tip sharpness. Two layers of micro needles (upper and bottom needle arrays) for the 2-D array were realized using simultaneous etching from the front and back sides of (110) silicon. In addition, microfluidic components were embedded in the micro-needle chip to inject or extract biochemical samples. The length of the micro needles was easily extended to 2200 μm, and the insertion forces of the single and arrayed micro needles were evaluated by pricking chicken breast flesh. In case of a micro needle having a tapered angle of 10° and tip end width of 1 μm, the insertion force per needle was as low as 15 mN, which is lower than those reported in previous studies.