PROJECT PLASTIC 2018 third place! Feasibility study of LDS antennas for hearing aid applications

With Laser Direct Structuring, it is possible to trace electrical circuits directly on the surface of plastics. This will increase robustness and design freedom when developing medical devices. This project is chosen as one of five projects that will be pitching at Plastic Engineering Day

This project has been chosen as one out of five projects that will be pitching at Plastic Engineering Day.
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In modern connected devices and especially in medical devices, it is required to create the smallest products possible without compromising functionality. This is possible taking advantage of the properties of plastics as supportive materials, combined with Laser Direct Structuring (LDS).

LDS antennas have never been implemented in hearing aid applications, which called for innovative designs and reliability testing, which paved the way for this thesis. The aim was to study the feasibility of LDS in hearing aid applications by creating innovative and robust connection designs between the PCBA and the LDS antenna. Hearing aids are also exposed to aggressive environments, so the reliability of the solution was evaluated in regards to main critical factors.

The satisfactory results of the project are presented through a systematic product development process, a physical prototype and tests. A final concept design is recommended, and interesting areas for future work are suggested.


University and the academic level of the project:

This project was acknowledged as a 30 ECTS weighted workload thesis, and as part of the contentment of the Master of Science degree in Engineering Design and Applied Mechanics at the Technical University of Denmark (DTU).

The work for this project has been realized from the 14th. of September 2017 until the 18th. of April 2018, excluding previous contact about the project definition with GN Hearing and DTU. The involved courses have mainly been micro manufacturing with polymers, materials science, manufacturing technologies for polymers.

The project was carried out at the Section of Manufacturing Engineering at the DTU in cooperation with GN Hearing. The study has been supervised by Aminul Islam (MEK) and Anders Michaelsen Hjermø (GN Hearing).


Which type(s) of plastics/production processes are used in your solution?

Different experiments are described in the project, where laser structuring is tested on Polyphtalamides (PPAs), Polycyclohexylenedimethylene Terephtalate (PCT), Liquid Crystal Polymers (LCP), and finally, the chosen polymer was the reinforced polyamide PA4T-GF30 called Fortii® LDS85.

For the solution, a functional prototype was made. It included the main part, which was injection moulded in an aluminium tool, designed by the undersigned. This part was then prepared for Laser Direct Structuring which was carried out with LPKF-LDS® equipment. Other parts were produced by additive manufacturing in the material Visijet M3 Crystal, and the assembly included manual soldering, pin connections and gluing.


More information:

This picture shows the final prototype which was tested.
This picture shows a rendering of the CAD model for the hearing aid including LDS antenna.
This picture shows the the machines involed in the LDS process and plating of the plastic parts.

PROJECT PLASTIC is a talent competition for engineering students. The purpose is to celebrate the talented students that as part of their degree lead the way in how to use plastic materials to create innovative solutions. The competition is being administrated by The Danish Plastics Federation.

Read more about PROJECT PLASTIC

The 11 best candidates for PROJECT PLASTIC 2018