Engineering students develop an implant to help relieve excess cerebrospinal fluid on the brain.
Pressure from excess cerebrospinal fluid on the brain is often relieved by surgically installing a shunt that carries the fluid to a reservoir. But when pressure in the reservoir itself is too high, the shunt needs a little help.
Student engineers working in the Oshman Engineering Design Kitchen (OEDK) have prototyped a solution: an implantable shunt pump that senses elevated intracranial pressures and pulls fluid away from the brains of patients with normal pressure hydrocephalus or idiopathic intracranial hypertension, even when reservoir pressures are high.
The “Brain Drain” team designed a negative-pressure pump system that gently lowers pressure when necessary, pulling fluid toward a reservoir in the peritoneal cavity, pleural cavity or the right atrium of the heart. Team members — mechanical engineering senior Samuel Brehm and bioengineering seniors Cooper Lueck, Patrick Bi, Haafiz Hashim, Irene Kwon and Bill Wang — are collaborating with Daniel Curry, a pediatric neurosurgeon at Texas Children’s Hospital, and faculty adviser Sabia Abidi, a lecturer in bioengineering.
The “Brain Drain” team designed a negative-pressure pump system that gently lowers pressure when necessary, pulling fluid toward a reservoir in the peritoneal cavity, pleural cavity or the right atrium of the heart.
The system will provide data via a pair of sensors. “One will be intracranial, and it will communicate with another sensor that measures the pressure in the peritoneum,” Bi said. “We toyed with the idea of having them be separate [unwired] units for ease of transmission, but we found the power consumption of any sort of measurement device as well as Bluetooth in the head was too great to justify it,” Lueck added. “So we’re running a set of wires parallel to the cerebrospinal fluid tubing to a device that is just underneath the skin right behind the ear. That will link up to the brain catheter to measure the pressure.” The battery-operated shunt pump can be wirelessly charged via an electromagnetic field and will communicate with external devices via Bluetooth.
The pump configuration is key, Brehm said. “We were going to design something custom, but then we found a really cool micropump that was membrane-based,” he explained. “We wanted it to be super low power and be able to generate enough of a negative pressure differential, as well as to allow cerebrospinal fluid to flow through while it was powered off.
“Certain pump designs have rollers that impede the path of the fluid when you turn them off, but we wanted it to act like a normal shunt even when it was off. This one flexes and pulls fluid in, and then it becomes stiff again and the fluid goes out the other valve. It works similarly to the valves and chambers of the heart.”
COVID-19 restrictions slowed but never stopped the team. “It was somewhat difficult at first getting things organized, especially last [fall] semester,” Hashim said. “I don’t think we met in person all at the same time once. But this spring, we’re mostly in Houston. Splitting the work into hardware and software teams helped a lot, along with staying on top of communications so everyone was on the same page with the components.”
In their final days before graduation, the students were miniaturizing the components to fit into a smaller casing more appropriate for implantation.