Stretchable PCB Technology

Regarding the technological development of the project, SINTEC worked for 2 years on the stretchable conductors, achieving many goals.  

Firstly, it has been fundamental the finalization of the ECG patch using the modular concept of reusable modules with HI_DCU (Bio2Bit) sensor board and LIR2032 rechargeable coin cell battery and active disposable cover tape with integrated ECG epidermal electrodes, as shown in the following figure. 

Connection with the modules has been ensured by Molex connectors mounted onto the flexible circuit board node. Moreover, the rigid-flex node collects the signal from epidermal ECG electrodes.  
Five pieces of the cover tape with ECG epidermal electrodes and one HI_DCU module and one battery were manufactured by handicraft, adequately packed and delivered to a partner of the consortium for further evaluation. 

Following some recommendations about the area of the integrated ECG electrodes. Those analysis bring to the creation of two series of devices for subsequent signal-to-noise measurement which are shown in the figure below.  

An ECG patch was made and delivered, using the modular concept of reusable modules with  HI_DCU (Bio2Bit) sensor board and LIR2032 rechargeable coin cell battery and active disposable  cover tape with integrated ECG epidermal electrodes. 

Moreover a development on the adhesive tape with digital technology has been achieved. Even though the polyurethane tape used as the outer rim of disposable cover tape provides a sufficient elasticity, pattern coated acrylic shows reduced adhesion to the skin especially while stretching exercise or in a constantly tensioned position. To increase the adhesion to the skin a fully coated adhesive tape can be used. The alternative is to use a soft silicone gel adhesive (SSA). SSAs exhibit a lower peel adhesion than acrylate adhesive resulting in less skin trauma on removal, which is particularly useful for fragile skin like that of babies or elderly patients. To maintain the high breathability, compliance and stretchability, SINTEC developed a novel adhesive tape with thin polyurethane film with the soft silicone adhesive deposited selectively using digital dispensing technology. All those technical adjustments, helped in the creation of a silicone gel’s structure much more efficient. 

A further fundamental step of this section of work, has been delivered with a comprehensive scientific study on the environmental performance of the device. This work was originally planned later in the project, but the input from the analysis was important for further planning of the stretchable monitoring devices with respect to the design of reusable and recyclable modules. The assumptions made will be discussed within the project to propose a continuation of the study on this kind of device.