Encapsulation Molded Coil
Connect/Collaborate
We were contacted by a medical device company that was developing an implantable electronic device, similar to a pacemaker, which would be used to treat obesity. They wondered if we might be able to provide a solution for an application they had where they needed to enclose an electro-magnetic charging coil for the device, in materials that needed to be comfortable and safe when in contact with a patient’s body.
When working on the development of a new product, Flextech encourages early involvement at the project’s onset. This customer understood the value of collaborating with a manufacturing partner early in the design and development process. In an effort to fully understand the functional and aesthetic requirements of the coil application, one of our technical sales representatives met with our customer’s product managers and engineers. Our sales person learned that the implantable device would stimulate the vagus nerve and cause the patient to feel less hungry.
Because the device is implanted in the body, it would need to be charged regularly using a process called inductive or “wireless” charging. An inductive electromagnetic coil would be worn by the patient over the location of the device for a required period of time in order to charge the device. The coil would need to be covered by a material that was comfortable to the patient, biocompatible and non-cytotoxic (safe for contact with human skin). It also required some method of securing it to the patient for the duration of the charging cycle. In addition, because it is a medical device, the coil assembly would have to have a clean, finished appearance.
We were challenged by our customer to develop a process, suggest appropriate materials, and to manufacture a part to meet all of these functional and aesthetic requirements.
Concept/Design
Our R&D engineers suggested a different solution. We proposed that we utilize our ENCAPSULATION MOLDING process wherein we would encapsulate the electromagnetic coil in the foam molding process. This process would eliminate the need for secondary sewing and wouldn’t require the use of sewn textiles that might absorb perspiration or other body fluids. We were also able to incorporate formed and sealed slots in the part so that the belt that holds the coil in place could be threaded through the part. The slot features eliminated the need for any supplemental hardware. In addition, the final assembly’s aesthetics would make it look like a medical device. We provided the customer with 3D part models and images of the coil assembly that we were proposing.
Our customer was very excited about our product design. They asked that we offer material options and provide quotations on the tooling and piece prices so that they could determine if our improved product design was economically viable.
Engineer/Develop
The tooling and piece prices we provided our customer with were acceptable to them, and they asked that we continue the development process. Because the charging coil needed to be comfortable when worn by the patient, we suggested a low density 2 lb/cubic foot cross-linked polyethylene foam. More importantly, the coil enclosure also needed to be covered by a material that was approved for medical skin contact and that would not absorb body fluids. We discussed the application with our material suppliers and ultimately suggested a urethane coated textile that had been tested to meet ISO 10993, which is the medical standard for materials that come in to contact with intact skin.
Once these materials were approved by the customer, we focused on the design of the tooling and fixtures that we would need to heat and mold the composite and encapsulate the coil during our ENCAPSULATION MOLDING process.
Prototype/Prove
Our engineering team went to work designing the tooling and fixtures we would need to build functional prototypes for our customer to evaluate and test. This project required the use of machined aluminum tool components in order to achieve the part geometry and definition the customer required.
In addition, we had to design and build fixtures that would allow us to register and secure the electro-magnetic coils during the ENCAPSULATION MOLDING PROCESS. Because this project would require us to laminate the urethane coated healthcare fabric to a closed-cell foam, we performed some preliminary testing of the LAMINATING process to make certain the fabric and foam would bond sufficiently to then be molded. We achieved a functional lamination bond of the two substrates and now had materials prepared for the completion of the tooling.
The prototype development process usually requires experimenting with the raw materials and process parameters and that was the case on this project. Once our tool shop completed the assembly of the tool, our R&D team was able to experiment with the required oven temperature, heating cycle, press tonnage and dwell time in order to encapsulate and seal the coil in the fabric and foam composite.
Ultimately, we were able to ENCAPSULATION MOLD a prototype coil assembly that we believed would meet our customer’s requirements. We provided several coil assemblies to our customer for their evaluation and testing. The coil assembly functioned as required, and following a few design iterations our customer was ready for us to manufacture the assemblies in volume and with production tooling.
Production/Delivery
Following several months of testing, the ENCAPSULATION MOLDED coil assembly was approved for production by our customer. In order to scale up for the manufacturing of larger quantities of coil devices, we needed to build multi-cavity production tooling and registration fixtures. Once the production tooling and fixtures were built, we provided first articles for our customer’s final approval.
In order to ensure that we provided our customer with quality coil devices, we also needed to develop a quality control program for every step of the manufacturing process. Utilizing our ISO 9001:2015 certification as a framework, we tailored a quality control process for this unique device assembly. We were then prepared to produce production quantities of coil assemblies for our customer’s product launch.
Project Outcome
The success of this joint product development effort between Flextech and our customer in the medical device market serves to illustrate the benefit of early collaboration when developing a new product.
Connecting and collaborating with Flextech in the initial stages of the device design allowed us to optimize the product development timeline. Our thorough understanding of the functional and aesthetic requirements of the device early in the process gave us the information we needed to provide concepts and designs that would be of interest to our customer.
After a design was approved, we were then able to engineer and develop a manufacturing process and specify materials suitable for the device construction. Armed with all of the information that our customer shared with us initially, we were able to minimize the number of design iterations during the prototype and prove phase of the development cycle.
Finally, once our customer tested and approved our prototype parts, we were able to scale up our manufacturing process and produce and deliver quality coil assemblies.
Contact us
Please contact Flextech if you have an idea for a new product you would like to develop, or a problem you would like our sales and engineering experts to help you solve. We look forward to an opportunity to work with you.
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