Henrik Rödjegård | Searcharxiv

arXiv2020

Graphene ribbons with suspended masses as transducers in ultra-small nanoelectromechanical accelerometers

Nanoelectromechanical system (NEMS) sensors and actuators could be of use in the development of next generation mobile, wearable, and implantable devices. However, these NEMS devices require transducers that are ultra-small, sensitive and can be fabricated at low cost. Here, we show that suspended double-layer graphene ribbons with attached silicon proof masses can be used as combined spring-mass and piezoresistive transducers. The transducers, which are realized using processes that are compatible with large-scale semiconductor manufacturing technologies, can yield NEMS accelerometers that occupy at least two orders of magnitude smaller die area than conventional state-of-the-art silicon accelerometers.

physics.app-ph↗

arXiv2020

Carbon dioxide absorption spectroscopy with a mid-infrared silicon photonic waveguide

Carbon dioxide is a vital gas for life on Earth, a waste product of human activities, and widely used in agriculture and industry. Its accurate sensing is therefore of great interest. Optical sensors exploiting the mid-infrared light absorption of CO$_{\mathrm{2}}$ provide high selectivity, but their large size and high cost limit their use. Here, we demonstrate CO$_{\mathrm{2}}$ gas sensing at 4.2 $μ$m wavelength using an integrated silicon waveguide, featuring a sensitivity to CO$_{\mathrm{2}}$ of 44 % that of free-space sensing. The suspended waveguide is fabricated on a silicon-on-insulator substrate by a single-lithography-step process, and we route it into a mid-infrared photonic circuit for on-chip-referenced gas measurements. Its demonstrated performance and its simple and scalable fabrication make our waveguide ideal for integration in miniaturized CO$_{\mathrm{2}}$ sensors for distributed environmental monitoring, personal safety, medical, and high-volume consumer applications.

physics.app-ph↗