The studied 3D electronic patch which is a three electrode sensor for measurement of muscle activity consists of two main parts: a two part housing for the electronics together with a battery frame cap embedded in an adhesive patch. The two parts are held together with snap latches. Adhesive (Loctite 4031) is used for assembly of the PCB in the housing and the battery in the battery frame. Housing and battery frame are prototypes of nylon 12 (polylaurinlactam) and made by SLS. The presented work aims at qualifying the prototype device for clinical test. Design changes of the first SLS prototype to minimize water penetration to the electronics are explained. The most important 3 design changes address the direct access for water (sweat) in the crevice between the housing and battery frame to the button cell battery area. By lowering the battery frame profile the patch adhesive can adhere to the house and thereby delay the water ingress. Likewise the water is delayed by an o-ring (Polyjet TANGO+ prototype material) placed in the battery frame close to the button cell battery. Between these two delays 124 square cavities capture / divert and delay the water on its way to the battery region. The capture is explained in terms of the Kelvin equation and wetting angles. Due to the potential corrosion and sensor signal dampening Nylon 12, Loctite 4031, TANGO+ and future potential housing and battery frame materials have been characterized concerning water uptake, diffusivity and wetting angle. Current preliminary environmental testing (damp/heat, sweat) is reported.
|Title of host publication||Proceedings of the IMAPS Nordic Annual Conference|
|Publication status||Published - 2008|
|Event||IMAPS Nordic Annual Conference - Helsingør, Denmark|
Duration: 14 Sep 2008 → 16 Sep 2008
|Conference||IMAPS Nordic Annual Conference|
|Period||14/09/2008 → 16/09/2008|