Hui-kai Zhang, Bowen Xu, Ziyao Jia, Bo Li, and Xi-Qiao Feng. (2024) Inverse design of three-dimensional multicellular biobots with target functions. Journal of the Mechanics and Physics of Solids 187:105634

Hybrid living biobots, consisting of active cells hold promise for significant applications as, for example, intelligent devices in medical engineering. However, the design and creation of living biobots with specific functions remain a challenge. In this paper, we propose a three-dimensional (3D) inverse optimization strategy based on the pixel topology optimization method, to design self-propelled living biobots with the function of biomechanical actuations. For illustration, we design several biobots composed of active and passive elements that mimic cardiomyocytes and passive epidermal cells sourced from such as Xenopus Laevis, human induced pluripotent stem cells or neonatal rats. The 3D topologies of the designed biobots are optimized by implementing the active constitutive relations of cells into the multicellular topological interpolation model. Effects of nutrient concentrations, elasticity, and anisotropic contraction of cardiomyocytes on their topologies and functionalities are examined. In addition, we unveil the living topological interfaces generated by the collective actuations of the optimized biobots. We show a potential of the collective biobots for high-throughput drug screening owing to their distinct biomechanical responses under healthy and sick states. The proposed inverse optimization method can be extended to design various functional multicellular biological systems, which impacts the studies of organ development, synthetic biology, and medical engineering.