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Wireless Medical Device Features Press-and-Fit Assembly

Article-Wireless Medical Device Features Press-and-Fit Assembly

Wireless Medical Device Features Press-and-Fit Assembly

A new medical device monitors human body functions wirelessly in a fit-and-press assembly that requires no adhesives or mechanical fastening.

Called ViSi Mobile, the wireless device is currently under development by DD Studio in concert with its client and manufacturer Sotera Wireless Inc. of San Diego, CA. It was unveiled at Canon Communications' MD&M East show in New York City this week.

Sensors attach to a patient's arm to monitor vital signs, such as blood pressure and heart rate so that clinicians can remotely monitor patients' information. The system also includes an eight-port charging station. One of the benefits of the device is the ability to capture continuous blood pressure measurement for ambulatory patients without the need for frequent cuff inflation. The system is compatible with standard Windows-based operating systems.

"When Sotera Wireless approached us with this medical-device design concept, it wanted the look and feel of a small, user-friendly consumer product, but had a number of specific demands. The device had to be chemical-resistant, durable, easy to clean and submersible. We weren't sure the design was possible," says Michael Swartz, growth strategist, DD Studio.

The device's lens, housing, printed circuit board assembly and connectors are made with Eastman Tritan co-polyester MX711. The cold-swaging capability of Tritan allows for fit-and-press assembly of the device, offering a tight, smooth, continuous fit between parts.

The co-polyester also provides resistance to chemicals used in disinfectants and cleansers without cracking or crazing. The material also exceeded durability requirements.

To protect the device from water and fluids found in the hospital environment, it had to meet IPX7 requirements (International Protection Rating) of withstanding water submersion for 60 minutes at a depth of 1 meter. DD Studio relied on compatibility samples and testing results from PolyOne to select GLS Versaflex OM 3060 TPE, which adheres to the co-polyester substrate to seal the device housing, including speaker port and microphone, from water seepage and protect internal electronics.

The housing components use a two-shot injection molding process, combining Versaflex TPE with the Eastman co-polyester substrate. In addition, insert-molded Versaflex is used to hold cables in place on the four device connectors. This material provides firm adhesion to the cable assembly and strain relief properties.

DD Studio and the product development team worked with Phillips Plastics Corp. to ensure the manufacturability of the design. Phillips Plastics Corp. of Hudson, WI took the designs DD Studio created and conducted a detailed DFM exercise and created market-entry prototype tooling.

Clinical testing on the device, which will be used in hospitals and homes, is now being conducted.

Sotera Wireless, which changed its name from Triage Wireless in 2009, recently secured $10.75 million of a $15 million round of venture funding to develop its wireless monitoring technology. Investors in the company are Qualcomm Ventures, Intel Capital, Sanderling Ventures and Apposite Capital.

"Sotera's novel technology for monitoring all of the vital signs will be a valuable safety net for seniors and people suffering from chronic diseases who want to live independently, but be connected to their doctor if there is a problem," says Gary West, founder and chairman of the West Wireless Health Institute (WWHI) in La Jolla, CA.

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