Case Study: Delta Development Team is Helping Deliver Critical Medical Supplies With the World’s Most Compact and Affordable Blood Refrigeration Unit

Unfortunately, having sufficient refrigeration capacity for the blood supply is only part of the solution. There is a litany of environmental hurdles that could breach the refrigeration unit and ruin the blood supply. 

Consider these challenges:

• What if there is a need to transport the blood to a scorching and arid environment? If that heat seeps through, the blood could spoil.
• What if the environment is too cold? The blood could also become frozen and unusable as a result. 
• Suppose the refrigeration unit is exposed to a sudden impact, such as from a car accident, or experiences a sudden change in pressure? Such conditions could result in a breach of the blood bags - spilling the contents and rendering the blood unusable.
• Or, imagine that the refrigerated blood needed to be stored for a long period of time in an environment in which there were no reliable sources of energy? 

In 2018, Engineers Bill Barg and Robert Futch were approached by the military to help solve some of these issues. Blood refrigeration units did exist, but the units’ inability to endure a variety of environmental hazards resulted in them being unreliable for the conditions in which soldiers must often operate. Having access to reliable blood storage technology makes all the difference to someone needing medical assistance.

Calling on their combined expertise in thermoregulation, mechanical engineering, and software engineering, Bill Barg and Robert Futch were well equipped to start designing a potential prototype solution. However, they lacked the direct experience to understand all of the potential issues that soldiers could face in the field of battle. Thankfully, they found Monti Leija, a veteran with combat service. His hands-on experience as a special forces medic in the field gave Barg and Futch the insight they needed to design and develop the optimal solution for blood storage and transport in combat environments. Together, they partnered to form Delta Development Team with the goal to manufacture their first product —the APRU (Autonomous Portable Refrigeration Unit)— which would be the world's most portable, FDA-listed, blood and vaccine refrigerator.

The unique cooling system of the APRU allows it to keep blood cool for 4 days (in moderate weather). The design is very durable, rugged, heat resistant, cold-resistant, chemical-resistant, UV-resistant, and can withstand the G-forces that would occur from it being airdropped out of a plane—a critical requirement given its intended use by the military.

The APRU can be solar-powered, which means that it can keep blood cool even when the operator is far away from other reliable sources of energy. This unit, which has been used by multiple branches of the military, is currently deployed and is helping field medics administer critical blood transfusions to those in need.

Delta Development Team saw an opportunity to improve on the refrigeration units that were currently being used in the field. They realized that many of these devices were jerry-rigged from standard products rather than being custom-built. A custom design would create a stronger, more robust product that could endure the rugged terrain soldiers often face. After winning an SBIR development grant,  Delta Development Team received the funding they needed to begin prototyping their product and paved the way toward mass production.

Once a functional prototype was developed, the team turned their attention to the problem of manufacturing the unit in quantity. They very quickly decided that the most efficient way to mass-produce the APRU was to use injection molding. Injection molding is the most cost-effective manufacturing method to produce plastic parts at scale. Delta Development Team did not originally use Xometry’s injection molding service to fulfill their needs. However, after working with another digital manufacturing company that couldn’t accommodate the large size of their mold, they turned to the team at  Xometry, who was able to accommodate. In addition, the Xometry team helped Delta Development Team navigate the mold and tooling processes and provided critical design for manufacturability (DFM) feedback that helped optimize the design to reduce costs and lower risks.

The APRU uses patent pending refrigeration technology, allowing it to be more rugged, more compact, and able to maintain a battery life 15x longer than competing blood refrigerators. Unlike its competitors, the APRU uses standard batteries and utilizes more efficient electronic expansion valves which are managed by a microchip and a miniaturized compressor. The APRU can be solar-powered as well, allowing it to maintain a charge out in the field when away from other sources of power. Once the unit is returned to an area where it can be recharged, it can be plugged into multiple power source options, including ambulances, planes, and power sources located at a base camp.

The APRU uses a polycarbonate blend for its exterior casing, which makes it both extremely lightweight and rugged enough to endure heat, cold, chemicals, UV rays, and intense vibrations. These capabilities, especially its shock readiness, were essential requirements, since one of the early sponsors, the U.S. Air Force, required that the APRU be capable of being airdropped behind enemy lines. The rugged design is compact but spacious enough to hold six bags of blood, but can also be used to transport vaccines, human organ tissues, and plasma.

Although Delta Development Team predominantly uses Xometry for its injection molding service, the start-up has also leveraged additional Xometry services to complement its designs, including our 3D printing and sheet metal cutting services.The heat sink of the APRU is fabricated from die-cast aluminum and utilizes aluminum sheet metal to provide a passageway for heat from the electronics to escape the device without any dust or water getting inside.
Inside the APRU, a variety of tiny HP Multi Jet Fusion printed parts are utilized that help facilitate airflow through minuscule air vents. This design choice comes in handy when the APRU is airdropped—as the air pressure changes, the air vents maintain the stability of the internal pressure, which keeps the blood bags and container from exploding. These parts were 3D printed because of the complex shapes required to connect the internal volumes of air and the exterior.