Graphenea and partners have successfully completed project NanoGraM that pushed the limits of nano/microelectromechanical (NEMS/MEMS) devices based on graphene. The project focused on three specific device concepts for potential future products:

• Graphene microphones
• Graphene-membrane pressure sensors
• Graphene-membrane Hall sensors

The target markets for these devices include portable electronics (smartphones, laptops), automotive, industrial, and smart homes, among others. The consortium consisted of four industrial and two academic partners: Infineon Technologies AG, WITec GmbH, RWTH Aachen University (Germany), Simune Atomistics S.L., and Graphenea (Spain).

Figure 1. Graphene microphone, pressure sensor and Hall sensor. Images courtesy of RWTH Aachen University, Infineon Technologies AG & Graphenea.

Graphene microphones have shown extraordinary sensitivity and operation from the audible to the ultrasonic parts of the audio spectrum, which offers novel functionality. For pressure and Hall sensors the expected benefits of using graphene include increased sensitivity (up to a factor of 100), robustness (up to a factor of 5), enhanced signal-to-noise ratios and the avoidance of hazardous materials in processing. The integration of graphene NEMS/MEMS sensors with silicon technology will enable smart systems that enhance the well being of people, food quality, traffic safety, pollution monitoring or homeland security. The research activities that took place as part of NanoGraM enabled a decisive technology lead for the industrial NEMS manufacturer and the participating SMEs.

Graphenea acted as a high-quality graphene provider and assisted the project goals by developing a semi-dry transfer process for suspended CVD monolayer and multilayer graphene on cavities and holes. Graphene was successfully suspended over holes up to 500 micrometers in diameter. This line of research enabled the introduction of a new product for Graphenea: suspended monolayer graphene on cavities.

Figure 2. Suspended monolayer graphene on a cavity. Images courtesy of Prof. Max Lemme and Stefan Wagner.

The project delivered three patent applications and at least seven scientific publications, with more in the pipeline. Apart from fabrication, characterization of large area graphene membranes was also taken to new heights, as detailed in the joint publication “Noninvasive Scanning Raman Spectroscopy and Tomography for Graphene Membrane Characterization”.

The project was jointly funded by Germany (BMBF) and Spain Basque Country as part of M-ERA.NET. It lasted 3 years and was worth in total € 1,960,244.