Dominique Brosteaux

Design of metal interconnects for stretchable electronic circuits

In this work, the design of flexible and stretchable interconnections is presented. These interconnections are done by embedding sinuous electroplated metallic wires in a stretchable substrate material. A silicone material was chosen as substrate because of its low stiffness and high elongation before break. Common metal conductors used in the electronic industry have very limited elastic ranges; therefore a metallization design is crucial to allow stretchability of the conductors going up to 100%. Different configurations were simulated and compared among them and based on these results, a horseshoe like shape was suggested. This design allows a large deformation with the minimum stress concentration. Moreover, the damage in the metal is significantly reduced by applying narrow metallization schemes. In this way, each conductor track has been split in four parallel lines of 15 mum and 15 mum space in order to improve the mechanical performance without limiting the electrical characteristics. Compared with the single copper or gold trace, the calculated stress was reduced up to 10 times.

Design and Fabrication of Elastic Interconnections for Stretchable Electronic Circuits

For biomedical and textile applications, the comfort of the user will be enhanced if the electronic circuits are not only flexible but also elastic. This letter reveals a simple moulded-interconnect-device technology for the construction of elastic point-to-point interconnections, based on 2-D spring-shaped metallic tracks, which are embedded in a highly elastic silicone film. Metal interconnections of 3-cm long were constructed with an initial resistance of about 3Omega , which did not significantly increase (<5%) when stretched. A stretchability above 100% in one direction has been demonstrated.

Design of Metal Interconnects for Stretchable Electronic Circuits using Finite Element Analysis

In this work, the design of flexible and stretchable interconnections is presented. These interconnections are done by embedding sinuous electroplated metallic wires in a stretchable substrate material. A silicone material was chosen as substrate because of its low stiffness and high elongation before break. Common metal conductors used in the electronic industry have very limited elastic ranges; therefore a metallization design is crucial to allow stretchability of the conductors going up to 100%. Different configurations were simulated and compared among them and based on these results, a horseshoe like shape was suggested. This design allows a large deformation with the minimum stress concentration. Moreover, the damage in the metal is significantly reduced by applying narrow metallization schemes. In this way, each conductor track has been split in four parallel lines of 15 mum and 15 mum space in order to improve the mechanical performance without limiting the electrical characteristics. Compared with the single copper or gold trace, the calculated stress was reduced up to 10 times.

Elastic and Conformable Electronic Circuits and Assemblies using MID in polymer

For user comfort reasons, electronic circuits for implantation in the human body or for use as smart clothes should ideally be soft, stretchable and elastic. In this contribution the initial results of an MID (moulded interconnect device) technology will be presented, showing the feasibility of functional stretchable electronic circuits. In the developed technology rigid or flexible standard components are interconnected by meander shaped electroplated metallic wires and embedded by molding in a stretchable substrate polymer, like silicone rubber or polyurethane. The meander design was supported by mechanical simulations in order to minimize the stress in the metal during deformation. In this way reliable stretchability of the circuits above 100% has been demonstrated. A simple stretchable thermometer circuit with 4 components embedded in Dow Corning Silasticreg PDMS silicone material has been built and proper operation has been demonstrated.

Biomedical Stretchable Sytems using MID Based Stretchable Electronics Technology

In order to fit human body, flexibility, or even better stretchability is requested for biomedical systems like implants or smart clothes. A stretchable electronic technology has been developed. This can provide highly stretchable interconnections fully compatible with PCB technologies. In order to prove the feasibility of complex biomedical systems like inner body implants or wearable systems, a variety of stretchable systems has been designed from sensor to power source systems.

Elastic Interconnects for Stretchable Electronic Circuits using MID (Moulded Interconnect Device) Technology

An MID (Moulded Interconnect Device) technology was developed for the production of elastic electronic interconnections. The stretchability is obtained using tortuous horseshoe shaped metallic wiring, embedded in a matrix of PDMS (poly dimethyl siloxane). In this way stretchable interconnects have been realized, consisting of 4 micron thick gold wires, embedded in 250 − 500 μm thick silicone material. . Stretchable interconnections, realised with this technology, have a maximum stretchability above 100%, with a stable resistivity of about 1.5 Ω per running cm for a track width of 100μm. A first simple operating stretchable electronic circuit has been fabricated, consisting of a blue LED driven by stretchable wiring. The technology is under development for use in biomedical applications in the first place, but has potential to be extended for various other applications like smart textiles, robotic skins, etc.

Low Cost, Biocompatible Elastic and Conformable Electronic Technologies using Mid in Stretchable Polymer

For user comfort reasons, electronic circuits for implantation in the human body or for use as smart clothes should ideally be soft, stretchable and elastic. In this contribution the results of an MID (Molded Interconnect Device) technology will be presented, showing the feasibility of functional stretchable electronic circuits. In the developed technology rigid or flexible standard components are interconnected by meander shaped metallic wires and embedded by molding in a stretchable substrate polymer. Several technologies have been developed to this purpose, which combine low cost and good reliability under mechanical strain. In this way reliable stretchability of the circuits above 100 % has been demonstrated. Enhanced reliability has been reached using an additional conductive polymer layer.

In vitro cytotoxicity testing and the application of elastic interconnection technology for short-term implantable electronics

An electronic device was fabricated consisting of 2 flexible electronic circuit islands, interconnected by a 7 cm long elastic interconnection, which could be elongated for at least 50%. This interconnection was based on gold conductor tracks following a 2-D spring pattern, embedded in a biocompatible silicone elastomer. The complete device was embedded in the same silicone elastomer. An in vitro cytotoxicity extraction test, executed on small test-samples in accordance with the ISO 10 993-1 guidelines, revealed that the applied silicone encapsulation to these samples functioned as a good seal for at least 8 days.