Delta Development crea un refrigerador médico portátil para ayudar a las tropas heridas

Dado que las industrias militar y médica suelen ser las primeras en beneficiarse de las nuevas tecnologías y dispositivos, sorprende enterarse de situaciones en las que las soluciones de baja tecnología son la norma la mayoría de las veces.

Uno de los escenarios que aún dependen de soluciones anticuadas es el transporte seguro de sangre, vacunas, muestras de virus y medicamentos con temperatura controlada, todo lo cual requiere un sistema de refrigeración confiable.

Some hospitals, for example, are still using beverage coolers filled with ice to transport organ transplants. The military has used coolers with ice to transport emergency blood supplies and also has experimented with small mobile refrigerators originally meant to store beer or soda.

“Everybody has their own workaround right now, but there is no reliable solution currently following all of the FDA’s best practices,” says Robert Futch, CTO of Delta Development. “These refrigeration units are not designed with medical device guidelines for transporting blood safely. When you’re in the middle of the desert in Afghanistan, you can’t predict how long ice or a cooling device will really last, or how much power it has left. But you definitely know it’s not going to stay cold forever.”

Delta Development is a Tucson-based R&D company specializing in military applications for cooling and heating systems in extreme environments. The product development company was contracted by the U.S. Air Force to design and manufacture the Autonomous Portable Refrigeration Unit (APRU) for deployment by medics on the battlefield.

Current military procedures require wounded troops needing blood to be evacuated by helicopter to the nearest base or field hospital. The APRU enables medics to replenish blood to patients faster on the ground.

Delta Development has been collaborating with the 48th Rescue Squadron at Davis-Monthan Air Force Base in Arizona for the design and testing of the device. The famed unit conducts combat search and rescue missions, serving as “guardian angels” during U.S. operations around the world. It also performs civil search and rescue, disaster relief, humanitarian aid, emergency medical evacuations, and counter-drug operations.

El frigorífico médico portátil se utiliza actualmente en equipos médicos militares, incluidos el Comando de Operaciones Especiales de los Estados Unidos (SOCOM), el Comando de Operaciones Especiales de la Fuerza Aérea de los Estados Unidos (AFSOC), los Rangers del Ejército de los Estados Unidos y las Fuerzas de Operaciones Especiales de Canadá (CANSOF), que han estado operando en ambientes de frío extremo.

Designing One of the “Smallest Refrigeration Systems in the World”

One of the Delta team’s biggest design challenges was centered around miniaturization: How do you shrink the typical 150-pound small hospital fridge to a more portable unit one-third to one-fourth its size and one-fifth its weight?

At a glance, the APRU (which holds six liters of blood) looks more like a large first aid kit or fishing tackle box than a refrigerator.

“What we should compare it to is what the medics are carrying right now,” says mechanical engineer Tim Gust. “They'll try to bring along these hospital refrigerators that are not really mobile devices. They have heavy batteries that come with them so they can be moved down the hall, but they weren’t meant to go out in a C-130 Hercules aircraft. They're not designed to be out in a tent in the desert – and certainly, they're not single-person carriable.”

“So we’ve developed one of the smallest refrigeration systems in the world,” he adds.

The compact 29-pound unit is 19” wide x 10” high x 10” deep. Its rechargeable battery lasts for 80 hours with a digital screen indicating remaining power. The dustproof and waterproof device is also operational in any orientation (on its side, upside down, tilted), runs in extreme hot and cold environments, and is designed to withstand the rigors of rescue operations.

El APRU tiene un calentador incorporado para evitar que su contenido se congele. El dispositivo pasó las pruebas de formación de hielo como parte de la certificación 4 veces mayor de la Asociación Nacional de Fabricantes de Productos Eléctricos (NEMA) requerida para los equipos exteriores. La unidad sigue funcionando incluso cuando se forma hielo en el exterior.

“One of the challenges was to make a rugged product that can withstand these high ambient conditions,” notes Gust. “And so part of making it rugged involved replacing the traditional condenser – that has a fan blowing air over the condenser – with just a large aluminum heat sink. That is pretty novel. Making that actually work took a lot of testing and FEA to really design the heat sink to reject that much heat.”

Having no fan means there are fewer moving parts to potentially break down.

“The passive heat exchangers are diecast aluminum structures that are very substantial and stiff and use convective natural cooling instead of active. So it’s completely different than your dorm fridge that would have a little fan blowing over some delicate aluminum fins,” he adds.

Onshape Helps Delta Accelerate Product Development

Para diseñar la unidad de refrigeración portátil autónoma, Delta Development eligió Onshape, la plataforma de desarrollo de productos de software como servicio (SaaS) de PTC que combina herramientas CAD sólidas con la colaboración en tiempo real y la gestión de datos.

As a small company with 13 employees, Delta places a high value on versatility. Most of the team’s five mechanical engineers are also proficient at either electrical or software engineering as well.

“Before we started using Onshape, we were also our own IT guys,” explains Delta Development chief engineer Bill Barg. “We were constantly running out of disk space or having one computer fail and dealing with issues about local installations of software and trying to keep up with the license file on some server. About 20 percent of our time was just dealing with administrative issues, you know?”

“Now it's such a liberation to not ever have to worry about what's on our server because it's all on Onshape's servers. Not having to worry about IT overhead has been a huge time-saver for us,” he adds.

Onshape’s real-time collaboration tools allow multiple engineers to work simultaneously on the same 3D CAD model in the cloud. Whenever one team member makes a design change, everyone else on the team instantly sees it. A comprehensive Edit History tracks who made what change and when, allowing teams to instantly revert back to any prior stage of the design.

«Siempre que describo Onshape a alguien, digo que es como los Documentos de Google de CAD y, al instante, me dicen que tiene mucho sentido ¿Por qué ellos (la industria del CAD) no lo han hecho ya?» " dice Futch.

“Being able to collaborate in a browser just makes CAD extremely more useful for a distributed team like ourselves. I previously spent 30 years doing it the old way and I’m very glad we decided to change our approach,” says Barg, who has used a number of file-based, on-premise CAD systems in his career.

Although its core design team is based in Arizona, Delta Development has an electrical engineer based in Montana and frequently partners with an injection molding company in Detroit.

“The ability to do mechanical design reviews remotely has been critical for us,” adds Futch. “When the COVID-19 pandemic forced us to work at home, we were able to continue as normal with our design process.”

Improving Life-Saving Equipment for Civilians

Delta’s engineering team is also currently developing a blood-warming device as a companion product to their blood-cooling unit. The new portable device would warm blood to body temperature in the field, reducing the risk of the patient getting hypothermia.

«A medida que desarrollamos estos productos con el escuadrón de paracaidismo, una de las cosas que más me entusiasma es la aplicación civil», afirma Futch, y añade que su equipo también está llevando a cabo algunos programas piloto con los departamentos de bomberos y los equipos de Life Flight en Arizona y Alaska.

Barg señala que con frecuencia le preguntan por qué nunca antes se había inventado un refrigerador portátil para almacenar sangre, especialmente porque la tecnología en sí misma está fácilmente disponible.

“The answer is that it took a special team of players here – engineers, retired soldiers and retired medics – to first put the importance on it,” he says. “This refrigerator is now ready to save lives in the battlefield. And it’s because of our partners who are retired soldiers who bring us new points of view.”

«También estamos en el comienzo de una nueva era en las capacidades de ingeniería, en la que podemos asumir una tarea extremadamente difícil y realizarla rápidamente a un precio razonable. Hay muchas formas nuevas de realizar este tipo de diseño de productos. Me refiero al modelado 3D, la impresión 3D, las comunicaciones más rápidas entre las personas que trabajan en diferentes lugares y la economía de ingeniería por encargo de muchos colaboradores diferentes que desempeña un papel clave», añade Barg. «Poder aprovechar estos nuevos enfoques de la ingeniería y utilizarlos para un buen propósito es muy satisfactorio».