Actuators, sensors, controllers: The robot-assisted flexible endoscope combines all three

The rise of robotics in medicine will result in more and more applications in this sector in the future. This necessitates the design of robotic systems that meet the specific requirements for the respective medical implementation. Scientists at the Institute of Medical Device Technology at the University of Stuttgart are developing the systems, components, sensors, and control technology to meet this demand.

Prof. Peter Pott is the Director of the Institute. In this MEDICA-tradefair.com interview, he introduces the focus of his current research project: a robotic flexible endoscope.

Prof. Pott, why does your research explore robotic flexible endoscopy?

Prof. Peter Pott: We want to support medicine in using robot technology to speed up, simplify, and make flexible endoscopic interventions safer. Our focus is on developing actuation and sensor technologies that are small and powerful, yet cost-effective to also permit the robotic-assisted application of single-use endoscopes. Single use in this setting is key because it is otherwise very expensive and elaborate to make these systems reusable or to at least provide adequate sterilization to meet hygiene standards for human application. Despite the lament over the use of resources and raw materials, which must be disposed after the intervention, it is smart to rely on single-use medical devices in this instance. That is why we focus on the small, lightweight and affordability aspects.

What was your basic scientific objective at the start of your work three years ago?

Pott: We pondered where we could apply our actuation technology to benefit a maximum number of people. Flexible robotics is a suitable application. Endoscopy is a procedure that has been used for over 50 years to diagnose and treat problems in the gastrointestinal tract. Since then, the process has essentially been the same – physicians use a manually controlled endoscope. Over the years, the latter has been modernized thanks to new camera technology, new light sources, and instruments. However, it remains a procedure that is complex for the physicians and uncomfortable for the patients. Robotics aims to make this intervention easier and safer for medical professionals and safer and gentler for the patient. By using slim and flexible structures, we foster smaller incisions and create systems that reduce trauma. In a nutshell: robotics in medicine is designed to make things better (and – let’s face it – also less expensive).

That is why we are studying the actuation technology of the relevant systems and are trying to facilitate certain movements, produce specific forces, and achieve explicit movement patterns at a specified speed. This is our benchmark.

Which actuation technology has turned out to be the most suitable for robot-assisted flexible endoscopy?

Pott: We identified the actuation technology right from the start. The challenge was and continues to be its adaptation to the requirements. We use twisted string actuators (TSAs). This basically involves an electric motor that twists two cords lengthwise. The helix formed in this process becomes shorter the further the bundle is twisted. This converts the rotational motion of the motor into a linear pulling movement. The benefit is that the actuator is very slim and not expensive. Unfortunately, meeting the requirements of the overall system is not quite as easy to accomplish in practical application as my description would suggest. However, our technology would make it possible to replace the tube-like flexible part that touches the patient after each use since TSAs are cheap, thus allowing the reuse of the motor component.

How is a robot-assisted flexible endoscope constructed?

Pott: The setup of a robot-assisted flexible endoscope resembles a conventional device. It features a light source, a camera, a working channel for the instruments, a proximal passive section, and an active distal tip. The only difference is that the active distal tip is not controlled through manual actuated wheels on the handle of the endoscope but is driven by the previously described mechatronic actuator system. A robotic arm holds the endoscope in position in relation to the patient, meaning this is no longer necessarily an active task for the surgeon. To perform more complex procedures in single-port surgery or Natural Orifice Transluminal Endoscopic Surgery (NOTES), the robotic systems are equipped with multiple instrument channels. The system is subsequently controlled via a type of cockpit and joysticks.