Technical assistance systems in medicine are creating enormous progress in treatment, thus improving quality of life. The basic idea is to support the physician in several applications such as minimally invasive surgery. Here, interventions are performed using surgical instruments through natural body orifices or through small incisions in order to reduce trauma and shorten the recovery time for the patient. The lack of direct interaction with the tissue results in the loss of the surgeon's tactile sense. Therefore, the integration of force sensors in such instruments is mandatory to re-establish the tactile sense through haptic feedback. Such sensor integration in assistance systems as well as in medical instruments is one of the main research topics at our department.
Needle Tip Force Sensor
Percutaneous needle insertion into soft tissue is required in many medical procedures such as brachytherapy or biopsies. Due to the small size of the needles (Ø1 mm) and the usually low to absent haptic feedback, there is a risk of damaging delicate structures such as nerves or vessels during the insertion process. We conduct research on the development of sensor-integrated needles for needle tip force measurements in order to provide haptic feedback to minimize tissue damage.
For measuring the needle tip force, specially developed silicon strain gauges are integrated into the needle tip due to their small dimensions (1.8mm x 1mm) and high sensitivity. In addition to the application of the sensor element in a thinned area near the needle tip (for further information we refer to the publication), a patented disruptive manufacturing approach (patent) is also pursued.
Robot-guided Needle Insertion
In addition to approaches such as haptic feedback in training scenarios or assistive means for interventions, a robot-guided needle insertion provides further advantages in terms of positioning accuracy. For this purpose, a 6-axis low-cost articulated robot was developed and manufactured using 3D printing (article), which was funded by the RMU Initiative.The cost-effective manufacturing offers optimal conditions for replications and for teaching purposes.
Active support of people with walking impairments by means of an adaptive knee joint orthosis is intended to effectively assist the user during daily movements of the lower limbs, thus coping with their individual daily lives. The use of parallel twisted string actuators serves to efficiently convert the energy applied by the motor into a defined torque in the knee joint.
In addition, a sensor array developed by our group is located in the sole of the shoe (patent). This allows measurements of the ground reaction forces and thus a determination of the ground conditions as well as the position and orientation of the ankle joint. As a result, the adaptation to the environment is further increased.
In order to support the user in time and in line with their needs, the knee joint orthosis has to recognize the user’s movements and movement intentions at an early stage. In this case, a convolutional neural network is used to determine the current situation depending on measured data of selected sensors (e.g. muscle activity, joint angle, ground reaction forces). For more information, we refer to the related publication (opens in new tab).