Mars International is pleased to launch a series of case studies which describe the technical issues faced by several clients and how they were solved using a customized engineering solution.
Our first case study, involves developing a programmable control system for a medical cryotherapy product used in the treatment and rehabilitation of patients.
Mars International client Aircast, now DJO Global, is a leading provider of patient care products designed to provide functional management of sprains and other injuries. Universal to their flagship cold therapy family of products is the Cryo/Cuff™ Cooler that connects through a tube assembly to any Cryo/Cuff™ for treatment of acute sprains, trauma, post-op, and rehabilitation. The cooler traditionally used gravity to refill the Cryo/Cuff™ with cold water and required manual intervention. Aircast then developed the Aircast Autochill® System which would automatically cycle the cold water between the cooler and cuff thus eliminating the need for manual recycling. This product would benefit their medical facility customers by reducing the hands-on time needed for cryotherapy treatment and rehabilitation of patients. The follow-on product was to develop a programmable Aircast Autochill® System which gave the user control of the key timing parameters of the system.
Aircast had chosen Mars International as their manufacturing partner for the printed circuit board they had designed for the Aircast Autochill® System. The board would control an electronic pump which would compress the air in the cooler to force chilled water into the cuff to maintain a constant cycling of the water through the Cryo/Cuff™. The timing parameters for cycling the pump were fixed in Aircast’s original design. With a successful manufacturing program underway, they turned to Mars International for their engineering design and development expertise for their next generation board. Mars International was asked to redesign the PCB to maintain existing chiller functionality and to add a microcontroller to provide programmability of the internal timing patterns. They were to develop the associated software code for the microcontroller as well.
Solution & Benefits
Mars International’s electrical engineers first developed a circuit specification which was discussed and agreed upon with Aircast. The engineering team chose an 8-bit RISC-based microcontroller with in-system programmable internal flash memory optimized for applications that require performance, power efficiency, and ease of use in a small package. The internal flash memory and on-chip debug capability allowed for a fast and cost-effective development effort. In addition, it provided a secure and cost-effective option for future in-circuit upgrades that could significantly cut time to market for additional programmable features. As part of the design process, the engineering team consulted with the purchasing organization to choose readily available low cost components for the design. They also evaluated components of the existing PCB that were hard to procure and considered replacement parts which could improve leadtime and cost. They chose to replace the existing slide switch with a lower cost alternative. In addition, the inclusion of a microcontroller allowed the 555 timer to be removed from the board.
From the specification and microcontroller selection, the Mars International engineering team developed schematics for the printed circuit board design. The software code was designed and optimized to meet the required functionality. The layout of the board was completed according to the physical constraints outlined in the product specification for compatibility with the existing product enclosure. Mars engineers developed a test methodology, specification and procedure for manufacturing. The bill of materials (BOM) was created and the product files were released to manufacturing for an initial prototype build. Initial prototypes were manufactured, assembled, tested, and delivered to Aircast for their evaluation and final product assembly. The prototypes were fully functional and delivered on production-quality PC boards.
Aircast was able to quickly and cost effectively bring the programmable feature to market for their very successful Autochill® product line by choosing to partner with Mars International for their expertise in hardware and software design. The programmable Aircast Autochill® System PCB has been in production for more than six years.
If you are interested in learning more about the customized engineering solutions available from Mars International, give us a call. We can help you solve even the most challenging engineering and manufacturing problems.