Two electronic modules dedicated to SINTEC were realized and tested in the first trials, leading to further improvements in fixing bugs and in the optimization of the tools used to collect the data coming from the device. The first electronic module was within 10 mm diameter and hold low power intelligence and communication with PPG, 3 DOE accelerometer and temperature sensor. The second and final module had in addition sensing for bioimpedance and ECG, and logging of data. With the logging, the module was larger. In addition, changing firmware for the commercially available HI and SensorTile has broadened the capabilities of the SINTEC platform, since each hardware provides different sensor configurations.
A fabrication protocol was established for rigid-stretch PCB based sensor nodes with wireless electrophysiological readouts (ECG monitoring). The protocol consists of assembling components, digital patterning of liquid alloy circuitry, dielectric encapsulant and soft skin adhesive on a soft stretchable substrate. A novel implementation is the use of sports tapes in the form of skin adhesive patches ensuring the reliable adherence of reusable electronic modules to the skin even during intense sports performance. The PCB-technology was demonstrated on a large-scale A4 format. The KPI was met as manufacturing was made of an A4-sized stretchable foil with two-layers of conductors with line width of 0.1 mm, 0.2 mm via interconnects, and a pitch of 0.5 mm.
Comparison between Bluetooth and Fat-IBC
We have mainly studied body-centric communication scenarios where Fat-IBC may be superior to BLE using physical and biological (porcine) models as well as human volunteers. Our Fat-IBC antennas need further optimization in correspondence to more specific user-case scenarios. Moreover, we have improved our physical phantom fabrication methods. Two advanced phantom models representing the abdominal cavity of an average human obese model and the thorax cavity of an average human athlete model with both anthropomorphism and physical realism has been developed and used as test platform.
Data handling and communication
The IoT Gateway was concluded and the integration of sensors and the development of end-user applications in the SINTEC Dashboard. Alas, in the demonstration phase severe problems in the connectivity occurred in parallel with hardware failures of the multiuse module. With the high time press at the final stages of demonstrations, all partners have made strong efforts to finalize the demos as good as possible. The IoT Gateway has developed to such a stage that it will be possible to push it further to commercialization.
On the comparative tests
Four SINTEC electronic multiuse modules with Sensor-Tile, Morfea3, HI and MOR4 have been tested. It was concluded that the ECG and PPG signals need to be logged so that the signals can be time synchronized for estimating blood pressure (BP). The BP algorithm was improved to extract the optimal features required to predict BP in a reliable way. Evaluation of system architecture confirmed that Fat-IBC communication was better than BLE transmission in data transmission through the human body. The Morfea3 was tested and compared with gold standard and state of the art products with excellent results in stability and precision. This is most probably due to the light and tight structure with sport tape securing it tightly to the body.
Demonstrators for Sports and Clinical applications
Preparations were made for testing the user platform, body sensor and gateways in laboratory conditions and real-life settings. These preparations included preliminary testing, creating protocols, and (in the case of the clinical applications) finding a clinical partner with whom the test can be performed. However, when initiating the actual demonstrations, new failure modes in both hardware robustness and communication were apparent and the demonstrations were severely delayed. Partners have concluded that they will continue their work also after the project, as the results are very promising but the time was not sufficient.