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.