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Customized Gearboxes for Medical Infusion Devices

In compact medical devices like portable infusion systems and on-body injectors, every millimeter counts. Unfortunately, off-the-shelf motion solutions can often be too bulky to fit these modern-day, battery-operated devices; this means that design engineers often find themselves at a crossroads, attempting to balance the application’s stringent size and weight requirements with available motion solutions. When this situation arises, custom-designed motion control solutions, including gearboxes, become critical to help customers successfully design their medical device to meet market requirements. Here we explore different customization options for gearheads.
Custom Housing, Custom Solution
Standard gearboxes often fall short when faced with unique envelopes as their mechanical structure is pre-determined. Custom gearboxes address this gap by providing flexibility and innovative designs to accommodate multiple application requirements, including space constraints, device duty points, and other specific considerations. It is also an advantage for the device designer to have a tailored solution with features unique to the needs of the device.
A custom shell will fit the device in a much leaner way than standard components, as the gearbox is specially sized to integrate with the other parts of the device like the driver PCB, device shell, and fasteners. Device components can even be integrated into the package as an additional method of streamlining. The cost structure can be kept under control by carefully blending standard components with custom components, manual assembly with semi-automated processes, and the specific quality requirements.
Rotating Motion
The gearbox’s drive shaft, which facilitates the motion, can be adapted to the device coupling, providing an easy installation. The typical torque transmission interface to the delivery mechanism will be via a pinion, a D-cut, or a specific solution. Depending on various factors such as torque, cost, and space constraints, the gearbox technology selected will typically be either spur or planetary. Spur gears systems are simple to mount and are efficient, as they only feature one friction point between each stage. Planetary gears, conversely, deliver a high torque density for their reduced envelope.
The selection or combination of these two design principles will be completed according to the application’s specific working points and motion scenario. The material of the gears is also influenced by the points mentioned, with different grades of plastic or metallic materials available. The latest environmental regulations, ROHS or REACH for example, are also considered during the selection process.
Linear Motion
If the application dictates the drive of a piston or any linear system, integrating a lead screw system in the gearbox has advantages. Options for the gearbox architecture are available for optimization, including a 180° spur gear stage to further reduce the motion footprint. Depending on the interface between the lead screw and the syringe drive, the motion can be accomplished via an external nut or integrated captive gearbox design.
Conclusion
Custom gearboxes are advanced motion solutions designed to enhance the success of medical devices in the market by offering superior features compared to standard off-the-shelf products. By engaging in design discussions in the early stage of a project, Portescap converts the medical device designer’s needs into a tailored, cost-effective motion solution. We look forward to connecting with you soon!