Delta Development crée un réfrigérateur médical portable pour aider les soldats blessés

Étant donné que les secteurs militaire et médical sont souvent les premiers à bénéficier des nouvelles technologies et des nouveaux appareils, il est surprenant de découvrir des situations où les solutions de faible technologie sont le plus souvent la norme.

L'un des scénarios qui dépendent toujours de solutions démodées est le transport en toute sécurité du sang, des vaccins, des échantillons de virus et des médicaments à température contrôlée, qui nécessitent tous un système de refroidissement fiable.

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.

Le réfrigérateur médical portable est actuellement déployé auprès d'équipes médicales militaires, notamment le Commandement des opérations spéciales des États-Unis (SOCOM), le Commandement des opérations spéciales de l'armée de l'air des États-Unis (AFSOC), les Army Rangers des États-Unis et les Forces d'opérations spéciales du Canada (CANSOF), qui opèrent dans des environnements extrêmement froids.

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.

L'APRU est équipé d'un dispositif de chauffage intégré qui empêche son contenu de geler. L'appareil a réussi ses tests de givrage dans le cadre de sa certification 4X de la National Electrical Manufacturers Association (NEMA) requise pour les équipements extérieurs. L'unité est toujours opérationnelle même en cas de formation de glace à l'extérieur.

“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

Pour concevoir l'unité de réfrigération portable autonome, Delta Development a choisi Onshape, la plateforme de développement de produits Software-as-a-Service (SaaS) de PTC qui associe des outils de CAO robustes à une collaboration en temps réel et à une gestion des données.

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.

« Lorsque je décris Onshape à quelqu'un, je dis toujours : « C'est comme le Google Docs de la CAO », et on me répond immédiatement : « c'est tellement logique ! Pourquoi (l'industrie de la CAO) ne l'ont-ils pas déjà fait ? » " dit 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.

« Alors que nous développons ces produits avec l'escadron de parachutisme, l'une des choses qui me passionnent le plus est l'application civile », déclare Futch, ajoutant que son équipe mène également quelques programmes pilotes avec les services d'incendie et les équipes Life Flight en Arizona et en Alaska.

Barg note qu'on lui demande fréquemment pourquoi un réfrigérateur portable pour la conservation du sang n'a jamais été inventé auparavant, d'autant plus que la technologie elle-même est facilement 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.”

« Nous sommes également au début d'une nouvelle ère en matière de capacités d'ingénierie, qui nous permettra d'entreprendre une tâche extrêmement difficile, rapidement et à un prix raisonnable. Il existe de nombreuses nouvelles façons de réaliser ce type de conception de produit. Je parle de modélisation 3D, d'impression 3D, de communications plus rapides entre les personnes travaillant sur différents emplacements et de l'économie des ingénieurs à la demande, dans laquelle de nombreux contributeurs jouent un rôle clé », ajoute Barg. « C'est très satisfaisant de pouvoir tirer parti de ces nouvelles approches de l'ingénierie et de les utiliser à bon escient. »