FEATURE MEDICAL ELECTRONICS
Miniaturised interconnects support rapid evolution in medtech
Bob Stanton, director of technology at connector design and manufacturing experts, Omnetics reviews the interconnect technologies helping enable advances in medtech
M
icro and Nano connectors for miniaturised flexible cables on new
biomed devices are increasingly common. Detector circuit chips and processors are transitioning from instrument boxes to inside cables or probes. Handheld ultrasound devices are being used to evaluate internal organs, from blood clot analysis to cancer testing. Digital displays are becoming portable and being shared in real time with patients. Sensor chips are used in clinics for processing blood cells to deliver immediate results during consultations. Circuit processor chips in the brain are helping amputees move legs and hands. From pharmacy products to neuromodulation implants, evolutions in micro-signal processing is enabling advancements in medtech.
PATIENT MONITORING Micro circular connectors enable quick- change probes and sensors for medical diagnostics. Overmoulded inserts serve as both connector and handle, with the end containing a thermistor that changes electrically with temperature. Surgeons insert the probe into the body to monitor the temperature of a patient’s blood and tissue, displaying it in real time onto a screen or strip-chart, providing early warning to avoid risk of adverse reactions during procedures and help with intervention. Connector inserts can be prewired with contact systems spaced as narrow as .635mm and moulded to various materials. Medical interconnect reliability and
quality are critical, starting with the use of highly reliable elements. For dynamic patient service environments, designers typically specify spring-pin and socket systems, assuring proven reliability and performance over wide ranges of shock, vibration and thermal changes. Spring pins are made of BeCu with high tensile strength (17,200ksi) to withstand the rigours of use and abuse. Pin and socket elements use a strong nickel-plated barrier, subsequently coated with 50µin of gold, before being inserted into insulator housings moulded from LCP (liquid crystal polymer), meeting the highest level of reliability testing in
24 DECEMBER/JANUARY 2019 | ELECTRONICS Figure 1:
Medical electronic practices are evolving through the use of wearables, skin sensors, neurological sensing and optical scanning techniques for body wellness
Figure 2:
New electronics used in prosthetic limb devices are necessarily miniaturised and ruggedised. Highly flexible, yet wear- resistant cables are jacketed and wired – and are now in demand for use in soft robotic exosuits
Figure 3:
Ultra-miniature PZN connectors
medical industries. Cables and wire systems use Teflon-insulated wiring, carefully laser stripped to avoid nicking, crimped into the back section of the pin for higher long-term reliability than soldering to the wire. The pin-and-wire set is inserted into ruggedised LCP insulator bodies and epoxied in place. For portable and miniature medical devices that require lower current flow and voltage, two cables can be combined to deliver both power and signal within one medical-rated interconnect. Safety ratings are improved with insulation and properly keyed connectors that cannot be missmated. Power is controlled within the same cable and is well isolated from electromagnetic noise. Many new medical instruments also provide imaging for doctors and radiologists. These imaging systems transmit
high amounts of digital data, with circuits often running at speeds of up to 5Gbps, demanding high speed digital connectors and special wiring to deliver high resolution imaging, saving time for medical practitioners.
New products are expanding device portability for daily patient use outside of medical environments. Cables and connectors are designed for patient wear, data collection and subsequent sharing with medical practitioners. New flat cable and connector systems fit into clothing to provide monitoring of key biometric information, similar to devices designed for NASA and military personnel. New electronics used in prosthetic limb
devices are necessarily miniaturised and ruggedised. Highly flexible, yet wear- resistant cables are jacketed and wired – and are now in demand for use in soft robotic exosuits. Medical exoskeleton systems are being tested to assist in rehabilitation, and in some cases, longer term support in walking for patients such as those born with spina bifida. Medical equipment in ambulances is often exposed to extremes of temperature during service, as well as rough handling, high strength pulls and sharp bends in cables. Connectors must withstand repeated connections and disconnections during use, which miniature spring-pin to socket technology serves well. Micro- and Nano-miniature connector and cable systems are rapidly expanding in capability, while reducing in size and weight. The advent of high density, low voltage chip technology has provided opportunities for fast and reliable systems to serve evolving medical requirements. New materials and methods of connector and cable design can now handle very high-speed digital signals, within minute spaces that demand reduced size and weight, while also increasing signal integrity and system ruggedness. Customised variations of current miniature connectors can be very rapidly developed and shared with medical device designers using computer models. Once approved, manufacturing data is automatically routed to machining equipment and manufacturing labs for first-article builds.
Omnetics
www.omnetics.com +1 763 572 0656
/ ELECTRONICS
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