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Human–robot interaction technology has contributed to improving sociality for humanoid robots. At scales far from human scales, a microrobot can interact with an environment in a small world. Microsensors have been applied to measurement of forces by flying or walking insects. Meanwhile, most previous works focused on the measurement of the behavior of insects. Here, we propose microrobot-insect interactions by soft microfingers integrated with artificial muscle actuators and tactile sensors, which has been developed for a haptic teleoperation robot system. A soft pneumatic balloon actuator acts as the artificial muscle, and a flexible strain sensor using a liquid metal provides tactile sensing. Force interaction between a pill bug and the microfinger could be accomplished. The microfinger (12 mm × 3 mm × 490 μm) can move and touch an insect, and it can detect reaction force from an insect. The measured reaction force from the legs of a pill bug as a representative insect was less than 10 mN. This paper presents a microfinger as an end effector for the active sensing of reaction force from a small insect. We anticipate that our results will lead to further evaluation of small living things as well as technology development for human–environment interaction.

Multiple sensors and actuators integrated in a small space, especially an elongated thin structure, require equivalent number of signal lines between microdevices, but there is limited space for signal wires. Thus, we propose a mechanism using a single microchannel where a liquid metal droplet moves and shuttles. A shuttling droplet switches multiple terminals of signal lines along a microchannel based on a traditional switching mechanism using a liquid metal droplet. Electrically conductive gallium alloy liquid metals (Galinstan) can flow in a microchannel due to their fluidity. The terminals consist of opposing electrode pairs in a microchannel. A change in a variable impedance connected to a terminal as a pseudo sensor can be read when a droplet flows in and connects electrode pairs. This paper presents switching and addressing objective terminals of chromium electrodes by a shuttling conductive droplet (500 µm in diameter and 10 mm long) in a microchannel (500 µm in diameter and 100 mm long). A demonstrated simple mechanism enables communication between multiple microdevices along a microchannel. We anticipate wide application of proposed mechanism toward a multiplexer, especially in microfluidic devices because of the advantages of utilizing microchannels as common microstructures for both microdevices and signal lines.

Palpation is widely used as the initial medical diagnosis. Integration of micro tactile sensors and artificial muscles enables a soft microfinger for active touch sensing using its bending actuation. Active touch sensing by pushing-in motion of microfinger enables to evaluate stiffness distribution on an elastic object. Due to its compactness, the microfinger can enter a narrow space, such as gastrointestinal and abdominal spaces in a body. However, a microfinger can only touch and sense limited points. We aim at efficient method for searching a stiffness singular part in an elastic object by the directional touch sensing of a microfinger. This study presents a microfinger for active touch sensing using bending and push-in actuation and proposes an algorithm utilizing directivity in touch sensing by a microfinger for efficient localization of the stiffness singular part in an object. A gelatin block structure with a small rigid ball was prepared and touch sensed by the microfinger. Consequently, the position of the buried rigid ball could be efficiently identified based on the proposed algorithm. This result implies that the proposed method has potential applications in endoscopic medical diagnosis, particularly in identifying tumor positions.