Light-powered photosynthetic living actuator

Highly compliant deformable soft actuators enable the engineering of adaptive life-like systems. Biohybrid living materials expand possibilities for autonomous, self-powered, environmentally responsive systems with easy biological integration. Here, we present a light-driven living soft actuator that integrates the photosynthetic microalga Chlamydomonas reinhardtii with a pH-responsive poly(3-(acrylamido)phenylboronic acid-acrylamide)/polyacrylamide bilayer hydrogel. When exposed to light, through photosynthesis and N-assimilation, the microalgae locally ionize the polymer network, causing the bilayer actuator to bend. In darkness, through respiration, the microalgae locally release CO2 that protonates the polymer chains, reversing the deformation. This algae actuator enables finely controlled and reversible motions, with a large bending amplitude achieved within 18 hours and an initial response time of 10-20 s, which is maintained over 10 cycles of continuous operation. We demonstrate light-controlled grippers, highlighting the potential of algae-powered actuation for sustainable and autonomous soft devices. Deformable actuators can be used for adaptive life-like systems, and biohybrid materials can expand the possibilities for responsive materials. Here the authors integrate microalgae into a pH-responsive hydrogel to achieve a biohybrid photoresponsive actuator.