Optimal System Design

Body energy harvesters produce unreliably small amounts of power and moreover at lower voltages in compare to other applications. On the other hand, local processing operation in body sensor nodes can be power hungry. Designing an optimal power converter includes low power blocks and techniques employed in circuit level as well as minimizing the loss of the system by trade-offs between switches sizing and working frequency.

Acceptable precision of EEG signal monitoring devices is maintained by placing an active amplifier and signal conditioning next to the electrodes. Those components are integrated into an active EEG electrode.

Thermoelectric generators (TEGs) directly convert thermal energy into electrical energy using the Seebeck effect and satisfy crucial requirements in wearables e.g. small form factor, robustness and maintenance-free operation without movable parts. However, due to the low temperature gradients, thermal harvesters worn on the body need to be highly optimized to meet the power requirements of a wearable system. The idea of zero-power active electrode combines micro-TEGs with active EEG electrodes. Therefore, an autonomous active EEG electrode is designed to contain an EEG electrode, Thermo-Electric Generator (TEG) harvester, TEG power converter and amplifier.

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Harvesting kinetic energy from low frequency body movements provides the additional energy required by the project. From a point of human compliance and device’s complexity, nanocomposite energy harvesting devices are found the most suitable.