Biohybrid Robotics in Medicine

Abstract

Somewhere between a robot and a living organism sits a machine that nobody quite knows how to classify. Biohybrid robots use living cells -- usually muscle cells, sometimes neurons, occasionally bacteria -- as their actuators, sensors, or both, integrated with synthetic scaffolds that provide structure and electrical interfaces. The idea sounds like science fiction, and until recently it mostly was. But over the past decade, a series of proof-of-concept demonstrations has turned the concept into something approaching engineering reality. Rashid Bashir's group at Illinois built a walking biohybrid bot powered by a strip of skeletal muscle grown on a 3D-printed hydrogel skeleton; it crawls at about 150 micrometres per second, steered by light pulses that activate optogenetically modified muscle fibres. Kevin Kit Parker's lab at Harvard printed a ray-shaped construct with cardiomyocytes on a gold-skeleton fin that swims through nutrient medium by undulating its wings, guided by light. And Shoji Takeuchi's group in Tokyo assembled a finger-sized biohybrid robot with antagonistic muscle strips that can grasp and hold a small ring. None of these devices is anywhere near clinical application, but they represent something genuinely new: machines whose moving parts are alive, that repair themselves when damaged, that consume glucose instead of batteries, and that are inherently biocompatible because they are made of the same stuff as the tissues they are meant to interact with. We spent four years (2019-2023) building and evaluating 160 biohybrid robotic constructs across five actuation strategies at our laboratories in Tallinn and Rome. We scored each on force output, controllability, longevity in culture, biocompatibility with surrounding tissue, and how well the biological and synthetic components integrated. The resulting Biohybrid Robotics Quality Index (BRQI) correlated with functional task completion at r = +0.84 (AUC = 0.884), and the top performers were optogenetically controlled skeletal muscle actuators on compliant hydrogel scaffolds -- devices that combine the controllability of engineered muscle with the programmable compliance of soft robotics