Tissue-embedded Sensors for Intelligent Bio-actuators
From Bio-hybrid Actuators to Bio-hybrid Robots
For biohybrid robots to be adaptive and intelligent, they require a closed-loop control system that combines bioactuators with sensors to monitor and regulate biomechanical states. Such feedback control systems are crucial in converting muscle-based bioactuators into dynamic, responsive systems. The bioengineered skeletal muscle tissue used as actuators in this research is exceptionally soft and small, making it challenging to incorporate real-time sensors that are soft, miniaturized, biocompatible, highly sensitive, and compatible with the electrical fields used to stimulate contractions.
Fiber-like Flexible Sensor
In collaboration with Dr. Frank Clemens’ team at EMPA, we developed a soft, fiber-shaped piezoresistive sensor that integrates seamlessly with engineered muscle tissue to monitor contraction states in a cell culture environment. Insulated for biocompatibility, this sensor has high sensitivity to detect strain changes typical of engineered muscle tissue (<1%) and effectively monitors the motion of contractile muscle constructs. By incorporating this sensor in a closed-loop system, we enabled the first proprioceptive biohybrid robot that can sense and respond to its contraction state autonomously.
Hydrogel-based Sensors
Conductive hydrogels, known for flexibility and tissue adhesion, offer exciting potential in bioelectronics and tissue engineering. In collaboration with Prof. Esther Amstad’s Soft Materials Group at EPFL, we developed a piezoresistive hydrogel optimized for mechanical sensing within tissues. This highly stretchable organohydrogel can be co-printed with muscle cell-laden bioink to create complex tissue architectures. Serving as a flexible strain sensor, it can monitor both localized and bulk mechanical signals, allowing for a 3D mapping of mechanosensing within tissue models. This hydrogel-enabled tissue platform has the potential to create biohybrid robots with sophisticated, distributed sensor networks and to advance our understanding of biomechanics in engineered tissues.
Why Sensorizing Muscles?
Gaining insights into 3D biomechanics is fundamental for accurately replicating tissue development processes in tissue engineering. However, integrating soft tissue with real-time mechanical sensors poses design challenges. We are actively exploring these sensor integrations, with promising applications in biohybrid robotics, advanced sensor technologies, bioelectronics, tissue engineering, and biomechanics research.
Authors Involved
This research was led by the collaborative team at the Soft Robotics Lab, ETH Zurich, including
Miriam Filippi
Aiste Balciunaite
Asia Badolato
Robert K. Katzschmann