This article presents an overview of the Peg Restrained Intrinsic Muscle Evaluator (PRIME) device developed by a team of students at the Rice University to measure the strength of a hand affected by nerve or muscle damage. Members of the PRIME team started work on the device in the fall of 2008. Up to that time, doctors commonly used a manual muscle test to measure hand strength. In this test, a patient is asked to lift each finger while the doctor presses gently down on it. Such a measurement is crude at best and totally subjective. The research team realized that it was important for their new device to rotate freely in the x–y plane and translate freely along the z-axis. Because of this freedom of movement, when the patient pulls on the load cell, the sensor can swivel so that the full force vector is measured. This project won the Innovation Showcase competition, and the team members received $10,000 in seed money.
Sometimes, the attitude of students compet. ing in design competitions is more pie in the sky than feet on the ground. But the students on the PRIME team from Rice University in Houston were anything but impractical. Their project was initiated by a request from a surgeon looking for a workable solution to a real-world problem.
The result of this focus was a win at the Innovation Showcase competition in June. I-Show, founded in collaboration with the National Collegiate Inventors and Innovators Alliance and the Idea to Product competition at the University of Texas, Austin, is an annual competition sponsored by ASME for college inventors and entrepreneurs. The finals were held in conjunction with ASME's Summer Annual Meeting at Palm Desert, Calif. For its winning entry, the PRIME team was awarded $10,000 in seed money. More importantly, the students received valuable contacts as they work to commercialize their idea.
"Doctors are contacting us asking when can they get one for their patients," said team member Steve Xu. "It's exciting."
Team members Jennifer Cieluch, Caterina Kaffes, Matthew Miller, Neel Shah, and Xu began work on the device in the fall of 2008. Gloria Gogola, a surgeon with the Shriners Hospital for Children in Houston had approached the Rice engineering department about developing a new type of device that could measure hand strength, which can be affected by nerve or muscle damage. Until now, hand strength has been measured by a clinical procedure called the manual muscle test: a doctor asks the patient to lift each finger while the doctor presses gently down on it. Such a measurement is crude at best and totally subjective.
Some devices have been introduced to measure hand muscle strength, but XU said that even these methods were plagued by large errors between observations. "Changes in muscle strength have to be 50 percent or better to become clinically meaningful," XU said. "That's enormous."
The device the students developed is called the Peg Restrained Intrinsic Muscle Evaluator. When the team began researching what technologies were in current use, members discovered a manual dexterity test that required subjects to pick up an object with a couple of isolated fingers, manipulate it in the air, and return it to the particular spot. The fingers were ·isolated through use of a simple pegboard.
"Of all the ways to isolate the hand," Xu said, "the pegboard really shines."
With the fingers well isolated, it was time to develop a force measurement system. The big hurdle was making sure that the force of the muscle could be read accurately. If the finger was pulling on the sensor from an oblique angle, for instance, it could give the false impression of weakness.
"We discovered that it was important for the device to rotate freely in the x-y plane and translate freely along the z axis," Miller said. Because of this freedom of movement, when the patient pulls on the load cell, the sensor can swivel so that the full force vector is measured.
The first iterations of the device were admittedly crude. One version involved peg holes drilled by hand. And the initial tests were conducted on classmates and friends. But in time more-polished versions were evaluated at the orthopedic surgery unit ofShriners Hospital. "The feedback we got from the doctors was incorporated in the final design," Miller said.
"When we saw the clinicians using the device," Kaffes said, "we realized that this wasn't just a senior class project anymore. It had real promise."
Kaffes added that the design process "really prepared us for what we'll have to do in the real world."
But the real world has been put off for the student team members, for now. They all graduated with bachelor's degrees in bioengineering, and given the state of the economy, graduate school seemed a more inviting prospect than the job hunt. Miller, for instance, has entered medical school at the University of Texas; Kaffes is staying at Rice to pursue a master's degree in engineering; and Xu is off tcJ Harvard Medical School.
As for the muscle strength evaluator, Xu said his team hopes to have a full utility patent filed on the device by the fall. And a medical cent er in Texas has agreed to evaluate the device and publish the results. "It's not unrealistic for us to get to market within a year or two," Xu said. That should qualify as extra credit.
Editor's note: The 2010 ASME I-Show will be held in conjunction with the ASME Annual Meeting,June 4 through 9,2010, in Pittsburgh. For details go to www.asme.orglevents/ishow.