Sometimes, it’s the simplest things that take the longest to master. Which is why a new haptic device that simulates the insertion of a needle into the skin is a boon for medical professionals and the patients they will ultimately treat.
For students learning how to properly administer treatment to a patient using a needle, technique is everything. Push too hard and you can damage the nerve, go at the wrong angle and you can cause serious pain to the patient. Inserting a needle is a delicate balance of pressure and precision. Proper training is essential.
At the Penn State Hershey Medical Center in Hershey, PA, most students learn in an apprentice-style model. They’ll watch a professional many times over, witnessing all different body types and circumstances. But the reality is that they can’t truly know what it feels like to puncture human tissue until they do it on their own. Many medical students wait until residency before they even get a chance to practice on a cadaver. This leads to a huge learning curve once they are in the field. That translates to a lot of room for error.
Jason Moore, associate professor in mechanical and nuclear engineering at Penn State University, and his team at the College of Engineering recognized this dilemma and decided to take on the challenge.
Moore’s journey began three years ago, in 2015, when his team built a robotic central venous catheterization simulator to train professionals on this procedure. The CVC robot is now fully integrated into the training program at Hershey, where it provides a more realistic experience for those entering the medical field.
Inspired by this success, the team applied for an ENGINE (Engineering for Innovation & Entrepreneurship) grant from Penn State to fund the commercialization of a low-cost solution that would allow students to train frequently and effectively.
“We really want to build up people’s strengths so they’re at a high level of proficiency before they go and do this on actual patients,” Moore says. “Our concept for a haptic needle simulator would give them realistic force sensations so they could feel what it's like when the needle enters the body, allowing them to adjust their angle and acceleration as needed.”
With the CVC robot, a student can actually feel the motion and force just by holding the device in position. The robot interacts with the student, simulating the resistance and location of blood vessels in the body. This enables students to learn the force and placement needed to successfully insert a needle into a patient.
To make a less expensive haptic needle simulator, the design team ditched the robot. Instead, Moore and his team found a clever way to simulate the forces acting on a needle without the sensors, servos, and feedback controllers found in robots.
Their haptic needle mimics a syringe, much like the one used in an epidural procedure to deliver anesthesia to the membrane surrounding the spinal cord during childbirth. When pressed onto a surface, the needle retracts back into the device instead of puncturing the surface it is pressed into. As the needle goes back into the syringe, it punctures the inside of a cartridge, which has anywhere from two to six discs in it.
The discs have organic and inorganic material, such as cowhide and polymer mesh, that give the tactic feeling of layers of tissue. As a whole, the cartridge can be taken out and replaced to mimic different tissue profiles. So, depending on the procedure on which a student wants to train, the cartridge could have several discs that create a sudden build up and release of force as the needle punctures through different layers of tissue.
“In the case of a procedure like an epidural, it's very important in this rise and release of force that you don't overshoot,” Moore says. “It requires a steady motion forward so you cannot let your hand jerk forward when you break through the layers of tissue.”
To help students understand this feeling and improve their skill, the device is hooked up to a computer program which prompts the student on the angle and acceleration needed to achieve the desired results.
The engineers outfit the needle with a small gyroscope and accelerometer to sense position and pressure. System software uses this information to provide real time feedback, so students can see their movements clearly.
The program also trains students, using red and green zones to show where they need to correct the position and force on the needle. When they’ve completed the procedure, the program provides a report on how steady they were and whether or not they met their targets.
Overall, the concept is simple. It has already been tested by numerous medical professionals at Hershey, whose feedback helped narrow down the exact feeling of inserting a needle so that the device would be as realistic as possible.
The device, as it is now, would only cost about $100. This is inexpensive enough to allow training programs to buy multiple devices, so students can start learning to master the needle earlier in their career. Giving them more time to practice may reduce the learning curve when they’re finally doing clinical work on their own.
The cartridge concept could potentially be used in future designs, Moore says. But getting it to mimic the feeling just right will take many more months of calculations. His team will also have to record the reactions and experiences of professionals and those still in training to truly perfect the design.
When the device is ready to go to market, Moore and his team are considering starting their own company to get the product distributed nationally.
Moore looks forward to a future designing all kinds of low-cost training products that will make the transition for young medical students into the surgical unit much more seamless. No room for error means better peace of mind for patients.
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