Nano & Micro Connectors Improve Performance in Custom Prosthetic Applications

Customer Challenge

A leader in prosthetic manufacturing focuses on serving patients with limited mobility due to amputation. Their products include microprocessor knees, mechanical knees, microprocessor ankles, feet, accessories, and other supplies. The customer initially approached Aptiv needing an interconnect solution for a highly customizable knee prosthesis.

Traditional mechanical knees use hinges to replace knee joints, often resulting in a less natural walking pattern. Limited space within the prosthetic application also requires a compact design and durable components. The customer needed help with the rising cost of connectors and was looking for a flexible supplier to meet their demands.

Challenge Review

The customer had omitted specific connectivity between the knee gyro and the shin and only had a specific space envelope for the feedthrough. Additionally, tolerance issues with the previous design and cables resulted in them not mating correctly.

Aptiv was tasked with developing an interconnect solution to address the customer’s issues while also improving the application’s overall performance.

Aptiv Solution

Aptiv offered the customer our nano circular, micro circular, and custom cable assemblies solutions. For the micro circular connector, the micro contacts were per MIL-STD-83513, with a current capacity of 3 amps and 0.05″ contact pitch. For the nano circular connector, nano contacts were per MIL-STD-32139 with a current capacity of 1 amp and 0.025″ contact pitch. The key features of the connectors requested by the customer were lightweight and high reliability. Additionally, our team considered the customer’s request to minimize the amount of wicking when applying epoxy to the rear of the micro circular connectors.

An improvement to the design included keyed mating, which prevents mismating by controlling the mating orientation with cutouts. Our overmolding design also addressed the need for strain relief where the cable terminates at the connector’s weakest point, a key indicator on top of the connector to show where its top is located, as well as grip and physical protection of the termination area. Additionally, Aptiv's capabilities feature REACH and RoHS compliance, non-magnetic components, mixed signals, robust properties, IP-67 and IP-68 ratings, EMI and abrasion protection, and snag-proof designs.

Improvement

Aptiv design helps amputees with the security and dependability of their prosthetic application. Our connectors helped create a personalized, adaptable device that can switch prosthetic modes and responds to the user’s needs when encountering various terrain. The limbs and joints are microprocessor controlled, allowing them to mimic natural muscle resistance by adapting hydraulic resistance levels. It ultimately helps optimize stability when standing and walking on slopes and uneven terrain. Our precise tolerances to the contacts and outer diameter of the connector enhanced the application’s overall functionality.

Most importantly, the result of this newly designed connector improved the performance that the customer can count on. Aptiv understands the need for continuous design improvements that align with innovation and technological enhancements for medical devices and offers options for design customization as needed.