Biology subjects

Bawa, M.

Publications and source records attributed to Bawa, M..

4 recordsLinked to original sources

bioRxiv2026

2D Skeletal Muscle Thin Film Actuators Enhance Efficiency of Biohybrid Robots

Biohybrid robots combining compliant synthetic support structures with biological actuators could enable future applications ranging from precision microsurgery to unmanned exploration. Machines actuated by living skeletal muscles are capable of adaptive behaviors, such as sensing and responding to environmental stimuli in real-time, offering functional advantages over non-biological actuators. However, typical skeletal muscle-powered biohybrid robots depend on 3D tissues which require large cell volumes and offer limited control of muscle fiber alignment, thus reducing efficiency of force generation and transduction. Here, we present a locomotive biohybrid robot powered by 2D monolayers, or thin films, of precisely aligned skeletal muscle fibers on a micropatterned hydrogel skeleton. We demonstrate how varying skeleton design parameters, ranging from material stiffness to microscale topology, impacts muscle fiber alignment and resultant actuation strains, generating forces 10X higher than previous 2D skeletal muscle actuators, improving untethered actuation longevity by [~]4500X from < 10 minutes to > 30 days, and increasing efficiency of muscle force output (force per unit volume of muscle) by 20X as compared to 3D muscles. Utilizing our optimized design for skeletal muscle thin films, we create a multi-limbed robot composed of independent muscle-powered fins capable of on/off control and frequency-dependent speed control. With these control inputs, we achieve steered multi-directional locomotion at speeds up to 4 body lengths per minute in straight movement and 1200 degrees per minute in rotational movement, highlighting potential for such actuators to be transformed into long-lasting functional soft robots.

bioengineering↗

bioRxiv2025

Biohybrid tendons enhance the power-to-weight ratio and modularity of muscle-powered robots

Biohybrid robots powered by tissue engineered skeletal muscle have historically relied on architectures in which muscle actuators are placed directly on skeletons, thus limiting the accessible design space for such machines. By contrast, native musculoskeletal architecture relies on tendons to bridge the interface between muscles and skeletons, enabling precise, space-efficient, and energy-efficient force transmission. In this study, we use a mathematical model of the muscle-tendon-skeleton interface to design a biohybrid muscle-tendon unit composed of tissue engineered muscle coupled to adhesive tough hydrogel tendons. We show how tuning tendon stiffness and pre-tension modulates actuator performance, measure fatigue characteristics of our actuators over >7000 cycles, and tune skeleton stiffness to increase force transmission muscles to skeletons by [~]29X. Furthermore, we demonstrate an [~]11X improvement in power-to-weight ratio of muscle-tendon units as compared to previous demonstrations of robots powered by muscles alone. This work validates a robust approach for designing, manufacturing, and deploying muscle-tendon actuators that promises to enhance the modularity and efficiency of biohybrid robots.

bioengineering↗

bioRxiv2024

Leveraging microtopography to pattern multi-oriented muscle actuators

Engineering skeletal muscle tissue with precisely defined alignment is of significant importance for applications ranging from drug screening to biohybrid robotics. Aligning 2D contractile muscle monolayers, which are compatible with high-content imaging and can be deployed in planar soft robots, typically require micropatterned cues. However, current protocols for integrating microscale topographical features in extracellular matrix hydrogels require expensive microfabrication equipment and multi-step procedures involving error-prone manual handling steps. To address this challenge, we present STAMP (Simple Templating of Actuators via Micro-topographical Patterning), an easily accessible and cost-effective one-step method to pattern microtopography of various sizes and configurations on the surface of hydrogels using reusable 3D printed stamps. We demonstrate that STAMP enables precisely controlling the alignment of mouse and human skeletal muscle fibers, and thus their force-generating axes, without impacting their maturation or function. To showcase the versatility of our technique, we designed a planar soft robot inspired by the iris, which leverages spatially segregated regions of concentric and radial muscle fibers to control pupil dilation. Optogenetic skeletal muscle fibers grown on a STAMPed iris substrates formed a multi-oriented actuator, and selective light stimulation of the radial and concentric fibers was used to control the function of the iris, including pupil constriction. Computational modeling of the biohybrid robot as an active bilayer matched experimental outcomes, showcase the robustness of our method of designing, fabricating, and testing planar biohybrid robots capable of complex multi-degree-of-freedom motion.

bioengineering↗

bioRxiv2024

2.5D Actuating Substrates Enable Decoupling the Mechanical and Biochemical Effects of Muscle Exercise on Motor Neurons

Emerging in vivo evidence suggests that exercise impacts peripheral nerves, but the difficulty of isolating and studying the muscle-specific impact on motor neurons in vivo, as well as the inability to decouple the biochemical and mechanical impacts of exercise in this setting, motivate investigating this phenomenon in vitro. In this study, we show that tuning the mechanical properties of fibrin hydrogels can generate stable 2.5D motor neuron and contractile skeletal muscle cultures that enable long-term efficient secretome harvesting from exercised tissues. Motor neurons stimulated with muscle-secreted cytokines significantly upregulate neurite outgrowth and migration, with an effect size dependent on exercise intensity. Actuating magnetic microparticles embedded within 2.5D substrates enabled us to dynamically stretch motor neurons and non-invasively mimic the mechanical effects of exercise, revealing that dynamic stretch has an equally significant impact on axonogenesis. RNA sequencing revealed different transcriptomic signatures between groups, with biochemical stimulation having a significantly greater impact on cell signaling related to axon growth and development, neuron projection guidance, and neuron-muscle synapse maturation. Our study thus leverages 2.5D actuating substrates to robustly validate a hypothesized role for muscle exercise in regulating motor neuron growth and maturation through both mechanical and biochemical signaling.

bioengineering↗