We present a microgripper actuated by a soft microactuator for manipulating a single living cell. Soft actuators have attracted attention in recent years because their compliance which can adapt to soft targets. In this study, we propose a microgripper actuated by soft thermoresponsive hydrogels. The thermoresponsive gel swells in water when the temperature is low and shrinks when the temperature is high. Therefore, the microgripper can be driven by controlling the temperature of the thermoresponsive gel. The gels are actuated by irradiating with infrared (IR) laser to localize heating. The actuation characteristics of the gripper were theoretically analyzed and we designed a gripper that gripped a ≈10 µm size cell. Additionally, we succeeded in actuating the fabricated microgripper with laser irradiation and gripping a single living cell.

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A light-driven gel actuator is a potential candidate for a single-cell manipulation tool because it allows cells to be manipulated while ensuring less damage. Moreover, a large number of actuators can be integrated into a microfluidic chip because no wiring is required. Previously, we proposed a method for cell manipulation using light-driven gel actuators. However, the system used in the previous work did not allow the targeted cells to be manipulated in real time because the system used in the previous work could only irradiate preprogrammed patterned light. Moreover, when a large number of gel actuators are integrated into a chip, the Gaussian distribution of the laser light source results in the response characteristics of the gel actuators varying with the location of the actuator. In this work, we constructed a system that homogenized the intensity of the patterned light used for irradiation, allowing multiple gel actuators to be driven in parallel in real time. The intensity-homogenized patterned light improved the variations in the response characteristics of the gel actuators, and as a result, we succeeded in actuating gel actuators with various light patterns in real time.

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