A physical soft tissue growth simulator for implantable robotic devices

In the development of surgical technologies, one of the challenges in their initial validation has been the creation of accurate bench-top tissue phantoms. Tissue phantoms made of elastomeric material have fixed mechanical properties and are not able to increase in size, so they cannot mimic growth process or change in mechanical properties of their real counterparts. In this work we present a novel real-time soft tissue simulator aimed at testing the in vivo dynamic behavior of robotic implants. The simulator is capable of reproducing mechanical properties of the biological tissue, e.g. viscoelasticity, as well as its metabolism, being able to grow up to 260 mm. A control strategy based on impedance control enables the simulation of changing mechanical properties in real-time, in order to recreate conditions such as fibrosis or tissue scarring. We finally show the platform in use with a soft implant. The electric actuation in conjunction with the 500 Hz control loop frequency guarantees fast and accurate response. We believe our platform has the potential to reduce the need for in vivo preclinical studies and shorten the path to clinical experimentation.