Freestanding Laser-Induced Graphene Ultrasensitive Resonative Viral Sensors

Abstract

Early and reliable detection of an infectious viral disease is critical to accurately monitor outbreaks and to provide individuals and health care professionals the opportunity to treat patients at the early stages of a disease. The accuracy of such information is essential to define appropriate actions to protect the population and to reduce the likelihood of a possible pandemic. Here, we show the fabrication of freestanding laser-induced graphene (FLIG) flakes that are highly sensitive sensors for high-fidelity viral detection. As a case study, we show the detection of SARS-CoV-2 spike proteins. FLIG flakes are nonembedded porous graphene foams ca. 30 μm thick that are generated using laser irradiation of polyimide and can be fabricated in seconds at a low cost. Larger pieces of FLIG were cut forming a cantilever, used as suspended resonators, and characterized for their electromechanics behavior. Thermomechanical analysis showed FLIG stiffness comparable to other porous materials such as boron nitride foam, and electrostatic excitation showed amplification of the vibrations at frequencies in the range of several kilo-hertz. We developed a protocol for aqueous biological sensing by characterizing the wetting dynamic response of the sensor in buffer solution and in water, and devices functionalized with COVID-19 antibodies specifically detected SARS-CoV-2 spike protein binding, while not detecting other viruses such as MS2. The FLIG sensors showed a clear mass-dependent frequency response shift of ∼1 Hz/pg, and low nanomolar concentrations could be detected. Ultimately, the sensors demonstrated an outstanding limit of detection of 2.63 pg, which is equivalent to as few as ∼5000 SARS-CoV-2 viruses. Thus, the FLIG platform technology can be utilized to develop portable and highly accurate sensors, including biological applications where the fast and reliable protein or infectious particle detection is critical.

Multiscale Elasticity of 3D Boron Carbonitride Foam for Tunable Mechanical Resisting Devices

“…Notably, the Oliver–Pharr model is valid for continuum materials. Previous studies showed that nanoscale structures, including nanofoams, obey continuum models. , …”

“…Previous studies showed that nanoscale structures, including nanofoams, obey continuum models. 34,55 Previous studies showed that the principal deformation mechanism in densely packed layered nanostructures is related to the relative slipping of the layers. 56,57 Therefore, the elastic properties of multilayered nanostructures are strongly influenced by interlayer interactions; namely, materials with strong interlayer forces will present higher stiffness than those with weak interlayer forces since the former materials are able to efficiently transfer shear stress between the layers.…”

Biomass‐Derived Laser‐Induced Graphene and Its Advances in the Electronic Applications

“…Researchers are currently using a mobile microcontrolled potentiostat and a LIGbased device to electrochemically quantify anti-SARS-CoV-2 antibodies in clinical blood samples. [97,98] Due to the conductivity of paper-LIG, it can be utilized for the sensing of temperature. [99] The resistance along this conductive path was then assessed in response to temperature changes between 20 and 45 °C, which were regulated by a Peltier element.…”

“…Researchers are currently using a mobile microcontrolled potentiostat and a LIG‐based device to electrochemically quantify anti‐SARS‐CoV‐2 antibodies in clinical blood samples. [ 97,98 ]…”

Laser-Induced Graphene Capacitive Killing of Bacteria

“…Graphene is a two-dimensional (2D) hexagonal lattice of sp 2 carbon atoms that are covalently bonded within two planar directions . In addition to its high thermal and electrical conductivity, flexibility, and mechanical strength, graphene has an exceptionally high surface area (e.g., ∼2600 m 2 /g) and intrinsic theoretical capacitance (21 μF/cm 2 ). − These properties perfectly poise this carbonaceous nanomaterial to be used within a broad array of applications ranging from electronics − (e.g., supercapacitors) and biotechnology to environmental technology − (e.g., renewable construction materials). − Within the spectra of environmental technology, examples of graphene derivatives have been shown to be antibacterial by many researchers over the years . The potency of graphene-based materials is especially true in the presence of an applied voltage as exemplified by laser-induced graphene (LIG). , However, the exact mechanism for the antibacterial activity such as the physical destruction of the cell membrane via direct contact of the bacteria with the surface structure/texture chemical microbial toxicity such as oxidative stress, or electrical effects of LIG or other graphene-based materials remains ambiguous and can be attributed to any combination of the various mechanisms.…”