Enzymatic biofuel cells promise green power generation from a variety of natural resources, yet these systems all suffer from time-dependent degradati on effects, in particular progress! ng inactivation of enzymes, wh...Enzymatic biofuel cells promise green power generation from a variety of natural resources, yet these systems all suffer from time-dependent degradati on effects, in particular progress! ng inactivation of enzymes, which severely limit the operati on al lifetimes of such power sources. To extend operational lifetimes, we introduce a method to magnetically exchange exhausted enzymes for fresh ones. To this end, anodic and cathodic enzymes or enzyme cascades are immobilized on carbon coated magnetic nanoparticles. Under the action of suitable magnetic field gradie nts, these nano particles are assembled on the respective stati onary electrodes, or released from the electrodes for collection and subsequent excha nge. We dem on strate this method on a fructose/oxygen con suming biofuel cell emplo ying fructose dehydroge nase and bilirubin oxidase as well as on anodic and cathodic cascades employing fructose dehydrogenase/invertase and bilirubin oxidase/catalase, respectively. The en zyme-modified nan oparticles support direct electro n transfer bioelectrocatalytic curre nts by wiring the redox active cofactors to the carbonaceous coating and from there to the electrode surfaces. The facile injection, assembly, and removal of enzyme-modified magnetic nan oparticles along with fuel solutio n provides a promisi ng approach to exte nd the operati on al lifetime of enzymatic biofuel cells without the need for exchanging entire systems including chambers and electrodes.展开更多
For guiding light on a chip,it has been pivotal to use materials and process flows that allow low absorption and scattering.Based on subwavelength gratings,here,we show that it is possible to create broadband,multimod...For guiding light on a chip,it has been pivotal to use materials and process flows that allow low absorption and scattering.Based on subwavelength gratings,here,we show that it is possible to create broadband,multimode waveguides with very low propagation losses despite using a strongly absorbing material.We perform rigorous coupled-wave analysis and finite-difference time-domain simulations of integrated waveguides that consist of pairs of integrated high-index-contrast gratings.To showcase this concept,we demonstrate guiding of visible light in the wavelength range of 550-650 nm with losses down to 6dB/cm using silicon gratings that have a material absorption of 13,000 dB/cm at this wavelength and are fabricated with standard silicon photonics technology.This approach allows us to overcome traditional limits of the various established photonics technology platforms with respect to their suitable spectral range and,furthermore,to mitigate situations where absorbing materials,such as highly doped semiconductors,cannot be avoided because of the need for electrical driving,for example,for amplifiers,lasers and modulators.展开更多
文摘Enzymatic biofuel cells promise green power generation from a variety of natural resources, yet these systems all suffer from time-dependent degradati on effects, in particular progress! ng inactivation of enzymes, which severely limit the operati on al lifetimes of such power sources. To extend operational lifetimes, we introduce a method to magnetically exchange exhausted enzymes for fresh ones. To this end, anodic and cathodic enzymes or enzyme cascades are immobilized on carbon coated magnetic nanoparticles. Under the action of suitable magnetic field gradie nts, these nano particles are assembled on the respective stati onary electrodes, or released from the electrodes for collection and subsequent excha nge. We dem on strate this method on a fructose/oxygen con suming biofuel cell emplo ying fructose dehydroge nase and bilirubin oxidase as well as on anodic and cathodic cascades employing fructose dehydrogenase/invertase and bilirubin oxidase/catalase, respectively. The en zyme-modified nan oparticles support direct electro n transfer bioelectrocatalytic curre nts by wiring the redox active cofactors to the carbonaceous coating and from there to the electrode surfaces. The facile injection, assembly, and removal of enzyme-modified magnetic nan oparticles along with fuel solutio n provides a promisi ng approach to exte nd the operati on al lifetime of enzymatic biofuel cells without the need for exchanging entire systems including chambers and electrodes.
基金We thank Antonis Olziersky,Diana Davila Pineda,Steffen Reidt,Ute Drechsler,Richard Stutz and Daniele Caimi for the help with the sample fabrication and Herwig Hahn,Marc Seifried,Norbert Meier and Yannick Baumgartner for the help with SOI etching.We acknowledge funding from the QuantERA projea RouTe(SNSF Grant No.20QT21_175389).
文摘For guiding light on a chip,it has been pivotal to use materials and process flows that allow low absorption and scattering.Based on subwavelength gratings,here,we show that it is possible to create broadband,multimode waveguides with very low propagation losses despite using a strongly absorbing material.We perform rigorous coupled-wave analysis and finite-difference time-domain simulations of integrated waveguides that consist of pairs of integrated high-index-contrast gratings.To showcase this concept,we demonstrate guiding of visible light in the wavelength range of 550-650 nm with losses down to 6dB/cm using silicon gratings that have a material absorption of 13,000 dB/cm at this wavelength and are fabricated with standard silicon photonics technology.This approach allows us to overcome traditional limits of the various established photonics technology platforms with respect to their suitable spectral range and,furthermore,to mitigate situations where absorbing materials,such as highly doped semiconductors,cannot be avoided because of the need for electrical driving,for example,for amplifiers,lasers and modulators.
