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How Tiny Artificial Muscles Could Be Huge Energy Savers

Electroactive polymer technology could help engineers make lighter longer-lasting medical devices.

Brian Buntz

Parker's EAP technology on display at MD&M West.
Parker's EAP technology on display at MD&M West.

Imagine a technology that could reduce the amount of energy used to power medical device applications by 25 to 100 times. An electroactive polymer (EAP) from Parker Hannifin's BioCare business unit could do just that, says BioCare's business unit manager, Mario Calvo. The technology, which was on display at MD&M West, is a good fit for pumps and valves used in medical device applications and other relatively low-pressure and low-flow applications.

Measuring a fraction of a millimeter, the stretchable EAP film changes in size and shape when activated by an electrical field. "We are targeting battery activated devices where the patient is wearing, say, an oxygen tank, an infusion pump, or something of that nature," Calvo says. "In many cases, 20-40% of the size of those device may be just the battery." This EAP technology could enable medical devices to be lighter and quieter while lasting longer on the same-sized battery.

Other EAP Applications

The technology also can be used for drug-delivery and lab-on-a-chip applications. In the latter case, small amounts of fluid are used to do some mixing with the reagent. The EAP technology is so thin that it can fit onto a credit-card-sized template used for lab-on-a-chip analysis.

"The key value of EAP is that it is very flexible, stretchable thin material. Think of Saran wrap," Calvo explains. It is unique in that it can conform to the body. "If you look at piezo or MEMS or other strain gauge technologies, they are all inflexible. You have piezo film technology that you can bend but you can't stretch it."

The ability of EAP to stretch is also useful in that the degree of movement can be correlated to bodily movement. When electroactive polymers' shape is physically changed, their electrical characteristics also change, and that can be correlated to bodily movement, opening up applications in the wearables market segment. 

Meet SensoNODE

The EAP technology could also be integrated with Parker's SensoNODE line of wireless pressure, temperature, and humidity sensors. "The areas where SensoNODE can take advantage of [EAP's ability to be used to monitor movement] would be a wearable device that can measure breathing or joint distension or retraction for rehabilitation or for patient monitoring applications," Calvo says.   

The wireless-based SensoNODE technology has a multitude of other applications and is compatible with six different styles of sensors.

"The novelty about it is that we can take a small lightweight sensor and connect it directly into an iOS device or connect it to a gateway up into the cloud and then send the information back to the user in a useful format," Calvo says.  

SensoNODE is being used today for infrastructure into the hospital, for example, or for measuring devices like the beds that are inflated with air.

It could also be used for rehab applications and for monitoring prosthetic limbs. "When you are putting the prosthetic onto the limb, the technology could be used measure how much squeeze you have on that," Calvo explains. "You don't want to have too little because then the prosthetic will move too much on the limb and cause irritation. But you don't want to have too much squeeze either, so that it damages that joint or that connection."

The compatibility of SensoNODE to be integrated into an iOS app is also notable. "We are launching a development kit EAP product coupled with the SensoNODE and what you will get there is an app you can customize yourself," Calvo says. "When you look at the interface or the dashboard of the app, you could represent the energy in a gauge format or an analogue format." A library of widgets will be available in a library, and those elements can be integrated with sensors and placed on a screen in a near infinite variety of combinations.

The company is also planning on launching another platform later this year called SensoNODE Scout. "It is a Web-based version where the sensors will communicate via a gateway. It would be able to see an infinite number of sensors throughout a facility or throughout the equipment that is deployed," Calvo says.

SensoNODE Scout could be especially helpful to monitor patients. It could be used, say, in a nursing home. "Say you want to put a sensor on the cushions that people are sitting on for a wheelchair or the beds. You can then see if the patient hasn't moved very much and may be developing bed sores," Calvo says. "Instead of [nurses] making the rounds to check on an individual, they may be able to get an alert to notify them that the individual hasn't moved or hasn't it made it to lunch that day." The technology could be used as a sort of early warning system powered by sensors.

Another place where SensoNODE could prove helpful is battling the problem of alarm fatigue in hospitals. "It seems like everything in a hospital has an alarm and they are always going off. "What we are looking to do with SensoNODE is not to just send an alarm but to send the right message to the right individual," Calvo says. "If you are in a hospital setting and you are supposed to be getting oxygen and the oxygen pressure is low, instead of just beeping, it would send an alert to the nurse station. But at the same time, it may send an alert to the maintenance department to come over and to fix the settings if it is an infrastructure problem."

The alarms don't necessarily have to be audible. "They may come via text, or a blinking light on the screen. There are a variety of different methods that would avoid sounding of an alarm that you always have in the hospital that the nurses often get desensitized to now."  

SensoNODE could also be used to combat alarm fatigue by using an escalation system. "So if you were supposed to get the alert, but didn't acknowledge it, we could have it send the alert to the next person in that chain of escalation," Calvo says. "You can continue to send the alert to a chain of individuals until someone acts on it." 

Refresh your medical device industry knowledge at BIOMEDevice Boston, May 6-7, 2015.

Brian Buntz is the editor-in-chief of MPMN and Qmed. Follow him on Twitter at @brian_buntz.

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