As stated in my previous post, tremors are a very common neurological disorder that affects millions of people worldwide. Urinary catheters are used to drain the urine from the bladder when someone does not have control of their bladder muscles. People with tremors who may need to use a urinary catheter include those who have MS or the elderly. Robots to aid with urinary catheter insertion are not currently on the market, yet many people may be faced with the need to insert a catheter while experiencing tremors. As a result, I am currently working on developing an assistive robotic device to help reduce the effect of a hand tremor during catheter insertion.
Currently only one product, designed by a senior capstone group from Virginia Commonwealth University[i], offers a solution to assist with catheter insertion. This device is a purely mechanical device and is tailored toward patients who have suffered from a spinal cord injury. I am currently building upon this design, in which I am increasing the automation of the device and developing techniques to help reduce the effect of a tremor. Using databases from the National Institute of Neurological Disorders and Stroke[ii] (NINDS) and the Society of Urologic Nurses and Associates[iii] (SUNA) I was able to develop a better understanding of how catheters are inserted into both men and women. From there I began to look into current proposed ideas for tremor suppression. Papers and current available technology used to counteract the effect of tremors have provided me with inspiration on how to dampen the vibration of a tremor in my device. The papers I used included: Upper Limb Tremor Suppression with 7DOF Exoskeleton Power-Assist Robot[iv], Soft Wearable Robot for Tremor Assessment and Suppression[v], and Mechatronic Device for Tremor Sensing and Cancellation for Accuracy Enhancement[vi], and Suppression of Hand Postural Tremor Via Active Force Control Method[vii]. Current technology available includes: Liftware[viii], and the Gyroglove[ix]. Based on these resources, I am planning on either using sensors that monitor the tremor and produce and equal and opposite vibrational reaction, using a mechanical device to counteract the tremor (such as springs and dampers), or exploring possible materials to help absorb the shock of the tremor. I am planning on using the weeks ahead to test which dampening effect works best for silencing the tremor.
I have designed a device that would look similar to a glue gun to assist in inserting the catheter. The catheter would be fed through a funnel in the rear of the “glue gun”. Once in position, a motor will run and the speed will be reduced via gear boxes. Two pulleys, connected accordingly to the gears, are spun at equal speeds in opposite direction to feed the catheter though the device and into the person. I have completed a demonstration of the design in which a switch is hooked up to an Arduino, which then controls the motor. The switch I am using has three inputs: forward, backward, and off, meaning the motor will turn either clockwise, counterclockwise, or turn off. The gear reduction reduces the speed of the motor from 120 RPM to 1 RPM, which is the feed rate of the catheter. A syringe system is also included in the device in which lubrication is pushed out from the syringe onto the catheter to provide the necessary lubrication for insertion. A rack and pinion system is used to drive the plunger of the syringe forward.
By reducing the speed of the motor, the catheter is fed into the body at a comfortable pace and prevents injury to the patient because the catheter is not being fed at an extreme rate. Future work for the weeks to come includes creating an emergency shut off system for the device to help prevent injury if blockages are hit while inserting, and testing different damping methods to reduce the effect of the tremor.
Overall, this device would allow someone who suffers from tremors and cannot effectively insert a catheter live more independent by allowing them to complete this task by themselves. By effectively reducing the tremor, the catheter will be inserted into the body more steadily and would prevent discomfort and injury to the person that the shaking motion could cause. Less discomfort for the patient would lead to peace of mind while completing this task which could make the catheter insertion process easier for the client.
Other applications for this technology may include modifying the device to help those with diabetes give themselves insulin shots. This would once again be helpful if the person had a tremor and needed to give themselves a injections throughout the day. Instead of a catheter, a syringe and plunger system could be placed where the catheter is being fed in the proposed device. The backward motion of the motor would allow the plunger to draw the insulin into the syringe and then the forward motion of the motor would drive the medicine into the body. In addition, this mechanism could be used as a training device to help teach younger children how to insert a catheter independently, regardless of whether they have tremors or not. The device may provide peace of mind to some while learning how to insert a catheter, but may also help guide the catheter into the body initially until the person is more comfortable with the insertion process. Hopefully my various tested methods for tremor suppression will also inspire new technology for those with tremors to live a more independent life.
Finally, it is hoped that this device could be modified to fit an individual’s needs. The handle of the device could be enlarged based on how well the individual can grasp object. Also, buttons and switches could be modified to best fit the client’s needs.
[i] Speich and A. Klausner, “The Cath-Assist: A Self-Catheterization Assistive Device”, Journal of Mechanical Design, 2015.
[iv] K. Kiguchi and Y. Hayashi, “Upper-limb tremor suppression with a 7DOF exoskeleton power-assist robot”, 2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2013.
[v] Gallego, E. Rocon, J. Ibanez, J. Dideriksen, A. Koutsou, R. Paradiso, M. Popovic, J. Belda-Lois, F. Gianfelici, D. Farina, D. Popovic, M. Manto, T. D’Alessio and J. Pons, “A soft wearable robot for tremor assessment and suppression”, 2011 IEEE International Conference on Robotics and Automation, 2011.
[vi] H. Kamble, B. Ahuja, K. Masurkar and E. Kulkarni, “Mechatronics device for tremor sensing and cancellation for accuracy enhancement in microsurgeries”, 2014 International Conference on Advances in Engineering & Technology Research (ICAETR – 2014), 2014.
[vii] S. Kazi, M. Mailah, and Z. MD Zain, “Suppression of Hand Postural Tremor Via Active Force Control Method”, 2014 International Conference on Robotics, Control and Manufacturing Technology (FOCOM – 2014), 2014. Kamble, B. Ahuja