High-level integration of the energy supply is a basic prerequisite for the development of energy-sufficient microsystems. We use the chip-integrated fuel cell and its cascading capability as an option for self-sufficient energy supply for a variety of application areas, such as supplying energy to self-sufficient sensor systems.
Chip-integrated, highly-miniaturized, energy-efficient, and environmentally-compatible fuel cells represent a new approach to supplying energy to self-sufficient sensor systems . However, these fuel cells typically only supply voltages of up to 0.9 V. To reliably increase the output voltage, for example, to multiple volts over a longer term, multiple fuel cells can be connected in series on one substrate. With this cascading approach, the chip-integrated fuel cells become viable for different application requirements.
The prerequisite for a monolithically integrated energy supply through integration of a number of chip-integrated fuel cells on one substrate is that the fuel cell layouts, the manufacturing processes, and the materials used must be specifically optimized. This makes it possible to reduce the required chip area and to guarantee a reproducible, stable functionality. So far, we have succeeded in integrating up to 56 individual fuel cells on a chip area of 1.6 x 1.6 cm², which corresponds to a capacity of up to 2.1 mW/cm². The functionality of the highly-integrated fuel cell cascades has been demonstrated for a broad temperature range from -50 °C to +60 °C, which addresses the varied application cases of the chip-integrated fuel cell for self-sufficient energy supply.