Portable and wearable healthcare devices represent growing, high volume markets for the medtech industry. Patient monitors are evolving from stationary equipment designed for a hospital bedside to small, lightweight, integrated devices designed to give patients the mobility to remain in their homes and communities while under a physician’s care. Advanced technologies are driving innovations in mobile healthcare delivery—exciting diagnostic and monitoring telehealth and eHealth devices that allow physicians to reach more people more efficiently, even in remote regions of the world. Optimal patient comfort and mobility depends on packaging more features into thinner, smaller devices. Developing reliable devices that perform seamlessly in non-traditional healthcare environments beyond the confines of clinical settings presents unique challenges for medical device designers.

Compliance Ensures Reliability and Safety

Fig. 1 – Circular connectors with medical-grade plastic housings have proven an economical option in a wide range of portable diagnostic and patient monitoring equipment.
Medtech is a highly regulated industry with stringent medical-grade guidelines for high-density medical devices used in home healthcare telemetry and portable applications. Regulations apply to material sourcing, manufacturing, and packaging processes. A number of industry regulatory and environmental ratings exist for electronic components, including U.S. Food and Drug Administration (FDA) registration, ISO 13485, ISO 10993, RoHS, and REACH. Suppliers may additionally adhere to ISO 9001 quality management and ISO 14001 environmental management regulations.

FDA and other industry specifications, including AAMI-53 and global safety standard IEC60601, UL/CSA, are critical medtech design criteria. FDA classification and general controls are based on the intended device use, and take into account potential risk to the patient. A Class II and III device will require stricter definitions for performance and risk management than a lower risk Class I device. Registered manufacturers adhere to stringent quality systems, including inspections, tracking, and traceability criteria. Supplier FDA registration provides added assurance of the quality and safety of the electronic components used in disposable, portable, and wearable medical devices.

Navigating the Interconnect Maze

Connectors are ubiquitous in devices across medical modalities, including imaging, therapeutic, minimally invasive surgical devices, implanted electronics, patient monitors, and sensors. Choosing interconnect technologies for a given application is a critical first step. In past designs, numerous connectors might have been required for multifunctional devices. Today’s connector options often combine copper power and signal, fiber optics, fluid or gas connections, even an RF antenna interface, all packaged in a single integrated interface. The right connectors can yield overall lower cost for the manufacturer, a more compact package, and improve healthcare provision. So it is important to successfully navigate the connector technology maze.

Before identifying connector styles, a designer needs to initially identify each connection type, whether board-to-board, wire-to-board, wire-to-wire, panel mount, or inline termination, in addition to receptacle through-hole or surface mount terminations. Criteria should specify number and type of interface contacts, as well as the associated cable configurations. Whether a cable is intended for an ECG, defibrillator, power, analog, digital, bandwidth, fiber optic, or some combination, will determine cable diameter, length, shape, and material options. In every design there are packaging size constraints, in addition to manufacturer preferences for the desired physical size of the end product and branding requirements, such as logo marking and serialization for tracking.

Connector specifications depend primarily on the intended use of a device in real-world environments. Application functions, plus any potential for misuse, jointly inform the physical properties desired in the connectors. Design demands are significantly higher in a portable device intended to allow a patient freedom of mobility. Portable medical devices must meet design specifications more akin to smart phones than traditional medical equipment used in clinical settings. Mating cycles for medtech device connections may range from a single-use connector in a disposable sensor to tens of thousands of mating cycles in an MRI coil or portable glucose monitor worn by a mobile patient 24/7. Devices worn or carried by patients must be built to perform under a very wide range of conditions. A range of temperatures and humidity levels exist in real-life settings, such as patient homes, where shock, vibration, and accidental drops also occur more often than in clinical settings where equipment is handled by professionals. (See Figure 1)

Connector Mechanical Specifications

Fig. 2 – High-performance and affordable custom-off-the-shelf circular connectors feature lightweight medicalgrade plastic housings to withstand autoclave and other sterilization processes.
A range of durable materials is suitable for lightweight portable and wearable medtech devices. Connector contact bases and platings are typically metal, with medical-grade plastic or metal body housing and strain reliefs. Gold plated contacts generally work best in harsh environments. While tin is more economical, gold plating offers the most reliable contact and mating cycles. Nickel-palladium-to-gold is also proven and accepted within the industry.

A properly designed device with regular un-mating of connector interfaces allows visual inspection to reduce debris build-up. If contaminants are observed they can be eliminated before impacting performance. Medical device sterilization, specifically exposure to sterilized wipes, gamma radiation, ethylene gas, autoclave, and Sterrad® process, also factor into material selection and design. Each sterilization method presents different exposure levels, chemicals, reactivity, and risks to connector integrity. Medtech applications typically require connectors resistant to fluid ingress, with most requiring an IP6 or IP7 rating level. (See Figure 2)

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