Research & Innovation

Stevens Seniors Develop Medical Device for Monitoring Surgery Patients under Anesthesia

A prototype medical device for the effective monitoring of surgery patients under general anesthesia that was designed by a team of Stevens undergraduate students may be faster, more accurate, more practical and less expensive than in-market alternatives.

Mechanical Engineering major Edan Golomb and Biomedical Engineering majors Kyle Ripley, Derek Smith and Jen Trinh – an interdisciplinary team of seniors at Stevens nicknamed AcceleroMetrix – have designed the TOF Clip, an “independent neuromuscular blockade monitoring device,” for their capstone senior design project.

Sixteen million surgery patients are administered anesthesia every year. In each surgery, the anesthesiologist must constantly measure the level of neuromuscular blocking agents – drugs which temporarily paralyze muscles so the physician can insert the patient’s breathing tube, allowing the patient to breathe while unconscious.

"If the anesthesiologist removes the breathing tube when the drugs are still present in the patient’s system, the patient will not be able to breathe because his or her diaphragm muscles will still be paralyzed,” said Golomb.

This mistake, which occurs in approximately 2 percent of surgeries, is extremely costly to a patient’s health and pocket book. In the most severe cases, a patient may be subjected to an extended stay in an intensive care unit which can cost $10,000 per night.

“If you have the right device, these complications are certainly preventable,” said Ripley.

Traditionally, most anesthesiologists have monitored the level of neuromuscular blocking drugs subjectively, which can result in human error. Others use two separate but interfaced products to understand when it is safe to remove the breathing tube – a nerve stimulator and a muscle response sensor – which are expensive, bulky and difficult to use.

“There really aren’t any monitoring devices for the presence of these drugs that are cost-effective, quantitative and accurate,” said Trinh.

With the help of Stevens Professor of Biomedical Engineering Vikki Hazelwood, the team’s faculty advisor, AcceleroMetrix designed a prototype for a small thumb-clip device to solve these problems called the TOF Clip. TOF stands for “Train of Four,” a measurement of the force of a muscle twitch which is used in clinical practice as an indicator of the level of neuromuscular blockade.

AcceleroMetrix’s TOF Clip enables physicians to accurately, affordably and objectively measure the level of neuromuscular blockade in a patient – i.e. if the paralyzing drugs are still preventing a patient from breathing properly. Consisting of five major components – a thumb clip, an accelerometer (or sensor), circuitry, a data acquisition device and a computer – it reliably monitors and measures muscle twitches without input from an expensive nerve stimulator.

AcceleroMetrix has worked closely on the TOF Clip with industry representative Dr. Glen Atlas, a Stevens Class of 1982 alumnus, a board-certified anesthesiologist, and an electrical engineer from the University of Medicine and Dentistry in New Jersey (UMDNJ).

“Dr. Atlas has seen firsthand the need for a cheap but effective device like the TOF Clip that reduces the risks of surgery under anesthesia and solves an everyday problem faced by anesthesiologists,” said Golomb.

Atlas hopes to begin early stage human clinical trials on the TOF Clip this summer at UMDNJ. If the product succeeds, he’ll help the team bring the TOF Clip to market.

Ultimately, AcceleroMetrix hopes to affiliate with distributors that sell neuromuscular blockade monitoring drugs, nerve stimulators and monitors, and sell the TOF Clip through their distribution networks of hospitals, anesthesiologists, surgical clinics and other healthcare providers.

“I see a great future for the TOF Clip,” said Trinh. “It’s a great alternative to the current products on the market.”

AcceleroMetrix recently won first place in a student poster competition presenting the TOF Clip at the Northeast Bioengineering Conference (NEBEC), held April 5-7 at Syracuse University. The competition included nearly 60 student posters from more than 30 universities representing the top biomedical engineering programs in the region.

"We are proud of these engineering students who have embraced their senior design project and demonstrated its value,” said Hazelwood. “I fully expect them to carry their experience into their careers to make significant and worthy contributions to society, and I’m really looking forward to that."

AcceleroMetrix will next display their prototype at the Stevens Innovation Expo on April 24 alongside hundreds of other innovative technologies, products, services and businesses designed by Stevens seniors in a wide range of disciplines to meet an industry need. For more information and to register, visit