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Recently, interest to develop soft robots that mimic flora and fauna in the natural environment has been growing in order to meet the demand for shortage in labor, working in hazardous environments, disaster management, health care and oceanography. Actuators that are made from soft materials, such as elastomers and hydrogels, are integral components of soft robots. Although, 3D printing is a versatile technique to fabricate prototypes, it is a well-known fact that 3D printing for soft materials is challenging. In this work, we present the fabrication and characterization of 3D-printed hydrogel soft actuator that mimics a jellyfish. The developed actuators consist of three parts; (1) Connector: which is the joint part between the main body of actuator and the inlet tube for air pressure, (2) Box: which is balloon-like inflation part and; (3) Base: which is connected to the Box. The results indicate that the normalized contraction ratio of the 3D-printed actuator is close value to that of moon jellyfish and is applicable to a jellyfish-mimic robot. Furthermore, it is observed that, the relationship between applied air pressure and injected volume is linear without balloon defects.

Abstract:To understand the behavior of cellular interfaces, it is important to clarify the effect of chemical compounds on artificial cell membranes. In this study, an aqueous acetonitrile solution was mixed with a suspension of lipid vesicles, and the changes in vesicle behavior arising as a result of acetonitrile application were observed. The fast Fourier transformations (FFTs) of the membrane waviness/crinkliness of the vesicles were carried out, and the membrane thermal fluctuations were analyzed. The experimental results show that the addition of acetonitrile molecules enhances the fluctuation of lipid membranes. In particular, the k = 2 mode fluctuation was significantly enhanced. This finding is expected to lead us to a further understanding of the fundamental properties of living cells.

We present fabrication and characterization soft tactile sensors composed of ion gel channel and elastomer (ion gel/elastomer sensors) and compared the sensing properties of the ion gel/elastomer sensors with ionic liquid/elastomer sensors. We have studied the relationship between the impedance and current frequency for the sensors. The impedance of the conductive channels surrounded by the elastomer is drastically decreased with increase in the current frequency in lower frequency regime and the impedance is approximately constant in the higher regime. We evaluated the change in impedance of the sensors against mechanical stimuli. It is observed that the optimum detection range of ionic liquid/elastomer sensor is 0–21 kPa of normal load, while the optimum detection range of the ion gel/elastomer is 0–510 kPa of the normal load. In addition, we investigated the effect of thickness of elastomer surrounding ion gel on impedance profile in response to applied normal pressure. The hysteresis of the relationship between the impedance change and the applied pressure is observed in loading and unloading procedures in the case of 3-mm thickness sensors while the hysteresis of the relationship between the impedance change and the strain is observed in the case of 6-mm thickness sensors.