Kidney stone removal is a complicated procedure. This product is a semi-automated ureteroscope, designed to reduce surgical time.
Boston Scientific is a medical device manufacturer specialized in minimally invasive surgical instruments. This project was initially taken up by Invent India design studio to develop a semi-automatic Ureteroscope for Boston Scientific, later I had the opportunity to redesign the concept with a new form and CMF design.
Automating the surgical steps that do not require human intelligence
Ureteroscopy is a tedious procedure requiring the surgeon to steer the probe precisely into the kidney and fire the laser. This process takes about 1 to 2 hours and a lot of precision and accuracy in firing the laser.
The aim is to reduce the surgery time and increase the precision during surgery. I was solely involved in this project to develop a reliable concept that the company could eventually produce.
A typical Ureteroscope construction involves a pulley with two lumens(thin wires) passing through two sides of the probe. Due to its unique construction, the probe bends with a fine curvature when the pulley is activated. This mechanism helps the surgeon to locate a stone by controlling the probe through the pulley handle.
Another application of the pulley is to dust a kidney stone with the laser. When a bigger stone is to be fragmented, a minute actuation on the pulley moves the tip with a small deflection. Since these two are considered as the most critical operations of Ureteroscopy, automating the pulley actuation was recognized as the significant challenge.
Since the probe bends after inserted into the patient’s body, the surgeon will have no control on the tip except to turn the tip by actuating pulley. To set the tip in a different axis, the whole device needs to be rotated from the outside. But this might not transfer the movement accurately. The risk with this uncertainty in control is that the laser may rupture the ureter wall if the firing was not pointed at the stone. So the challenge was to achieve high precision in stone dusting.
A true-scaled prototype was built integrating a few off-the-shelf components and a few manufactured components with enclosures 3D printed, and hand-assembled. This prototype was successful in demonstrating the procedures automatically. High-torque motors could achieve probe bending up-to 130 to 140 degrees, and the same engine was also able to deflect the tip precisely up to ±1.5 degrees. The stepper motor for laser feeding could feed as precise as 1mm advancement towards the stone.
The scope was designed to enable a seamless ergonomic interaction with the device to perform time tedious steps and automate the non-trivial steps of the surgical process to reduce the operating time. The proposed design demonstrated a precise Laser feeding mechanism with stepper motor for high accuracy and motor powered pulley to steer the catheter.