Sensitive capacitive pressure sensors based on graphene membrane arrays
Makars Šiškins, Martin Lee, Dominique Wehenkel, Richard van Rijn, Tijmen W. de Jong, Johannes R. Renshof, Berend C. Hopman, Willemijn S. J. M. Peters, Dejan Dav… 展开作者
Makars Šiškins, Martin Lee, Dominique Wehenkel, Richard van Rijn, Tijmen W. de Jong, Johannes R. Renshof, Berend C. Hopman, Willemijn S. J. M. Peters, Dejan Davidovikj, Herre S. J. van der Zant, Peter G. Steeneken
The high flexibility, impermeability and strength of graphene membranes are key properties that can enable the next generation of nanomechanical sensors. However, for capacitive pressure sensors the sensitivity offered by a single suspended graphene membrane is too small to compete with commercial sensors. Here, we realize highly sensitive capacitive pressure sensors consisting of arrays of nearly ten thousand small, freestanding double-layer graphene membranes. We fabricate large arrays of small diameter membranes using a procedure that maintains the superior material and mechanical properties of graphene, even after high-temperature anneals. These sensors are readout using a low cost battery-powered circuit board, with a responsivity of up to 47.8 aF Pa$^{-1}$ mm$^{-2}$, thereby outperforming commercial sensors.
In Micro-electro-mechanical Systems (MEMS) based pressure sensors and acoustic devices, deflection of a membrane is utilized for pressure or sound measurements. Due to advantages of capacitive pressure sensor over piezoresistive pressure sensors (low power consumption, less sensitive to temperature drift, higher dynamic range, high sensitivity), capacitive pressure sensors are the 2nd largest useable MEMS-based sensor after piezoresistive pressure sensors. We present a normal capacitive pressure sensor, for continuous sensing of normal and abnormal Intraocular Pressure (IOP). The composite mem…
Scale-up of flow-electrode capacitive deionization is hindered due to the reliance on thick brittle graphite current collectors. Inspired by developments of electrochemical technologies we present the use of flexible membrane electrode assemblies (MEA) to solve these limitations. We tested different carbon-fiber fabrics as current collectors and laminated them successfully with ion-exchange membranes. The use of thinner ion-exchange membranes is now possible due to the reinforcement with the carbon fiber fabric. Desalination experiments reveal that a MEA setup can achieve salt transfer rates e…
Unparalleled strength, chemical stability, ultimate surface-to-volume ratio and excellent electronic properties of graphene make it an ideal candidate as a material for membranes in micro- and nanoelectromechanical systems (MEMS and NEMS). However, the integration of graphene into MEMS or NEMS devices and suspended structures such as proof masses on graphene membranes raises several technological challenges, including collapse and rupture of the graphene. We have developed a robust route for realizing membranes made of double-layer CVD graphene and suspending large silicon proof masses on memb…
The ability to tune charge storage properties of graphene oxide (GO) is of utmost importance for energy conversion applications. Here we show that electrochemical reduction of GO is highly sensitive to the cations present in the solution. GO is reduced at lower potential in alkali metal chloride solutions than in alkaline earth metal chlorides. During the reduction, capacitance of GO increases from 10 to 70 times. Maximum capacitances of reduced GO are between 65 and 130 F g-1, depending on the electrolyte and the presence of conductive additive. We propose that different interactions of catio…
Increasing energy demands of modern society requires deep understanding of the properties of energy storage materials as well as their performance tuning. We show that the capacitance of graphene oxide (GO) can be precisely tuned using a simple electrochemical reduction route. In situ resistance measurements, combined with cyclic voltammetry measurement and Raman spectroscopy, have shown that upon the reduction GO is irreversibly deoxygenated which is further accompanied with structural ordering and increasing of electrical conductivity. The capacitance is maximized when the concentration of o…
Flexible pressure sensors are an attractive area of research due to their potential applications in biomedical sensing and wearable devices. Among flexible and wearable pressure sensors, capacitive pressure sensors show significant advantages, owing to their potential low cost, ultra-low power consumption, tolerance to temperature variations, high sensitivity, and low hysteresis. In this work, we develop capacitive flexible pressure sensors using graphene based conductive foams. In these soft and porous conductive foams, graphene is present either as a coating of the pores in the foam, inside …
Semi-permeable membranes are important elements in water purification and energy generation applications, for which the atomic thickness and strength of graphene can enhance efficiency and permeation rate while maintaining good selectivity. Here, we show that an osmotic pressure difference forms across a suspended graphene membrane as a response to a sucrose concentration difference, providing evidence for its semi-permeability. This osmotic pressure difference is detected via the deflection of the graphene membrane that is measured by atomic force microscopy. Using this technique, the time de…
Graphene is an atomically thin material that features unique electrical and mechanical properties, which makes it an extremely promising material for future nanoelectromechanical systems (NEMS). Recently, basic NEMS accelerometer functionality has been demonstrated by utilizing piezoresistive graphene ribbons with suspended silicon proof masses. However, the proposed graphene ribbons have limitations regarding mechanical robustness, manufacturing yield and the maximum measurement current that can be applied across the ribbons. Here, we report on suspended graphene membranes that are fully-clam…
Graphene has recently been shown to be permeable to thermal protons, the nuclei of hydrogen atoms, which sparked interest in its use as a proton-conducting membrane in relevant technologies. However, the influence of light on proton permeation remains unknown. Here we report that proton transport through Pt-nanoparticle-decorated graphene can be enhanced strongly by illuminating it with visible light. Using electrical measurements and mass spectrometry, we find a photoresponsivity of 10^4 A W-1, which translates into a gain of 10^4 protons per photon with response times in the microsecond rang…
Porous, atomically thin graphene membranes have interesting properties for filtration and sieving applications because they can accommodate small pore sizes, while maintaining high permeability. These membranes are therefore receiving much attention for novel gas and water purification applications. Here we show that the atomic thickness and high resonance frequency of porous graphene membranes enables an effusion based gas sensing method that distinguishes gases based on their molecular mass. Graphene membranes are used to pump gases through nanopores using optothermal forces. By monitoring t…
Microphones exploit the motion of suspended membranes to detect sound waves. Since the microphone performance can be improved by reducing the thickness and mass of its sensing membrane, graphene-based microphones are expected to outperform state-of-the-art microelectromechanical (MEMS) microphones and allow further miniaturization of the device. Here, we present a laser vibrometry study of the acoustic response of suspended multilayer graphene membranes for microphone applications. We address performance parameters relevant for acoustic sensing, including mechanical sensitivity, limit of detec…
Multilayered graphene-based nanoporous membranes with electrolyte incorporated between individual sheets is a unique nano-heterostructure system in which nanoconfined electrons in graphene and ions confined in between sheets are intimately coupled throughout the entire membrane. In contrast to the general notion that the electrolyte gating is unlikely to appear in multilayered graphene stacks, it is demonstrated in this work that the electrolyte gating effect in monolayer graphene can be transferred to its corresponding multilayered porous membranes. This gating effect presented on each indivi…
The data by Q.Yang et al suggest absence of "ultrafast flow" of solvent across graphene oxide (GO) membranes. The "ultrafast flow" is result of using unrealistic geometrical model with close packed hole-free micrometer sized GO flakes providing only 0.1 % of area in each layer available for permeation. The data by Q.Yang et all demonstrate that at least 3-5 % of total layer area are available for permeation in real GO membranes due to holes between irregularly shaped flakes. At least 2-3 percent of area also needs to be added to the permeation cross section due to holes and cracks in GO flakes…
The bending rigidity of two-dimensional (2D) materials is a key parameter for understanding the mechanics of 2D NEMS devices. The apparent bending rigidity of graphene membranes at macroscopic scale differs from theoretical predictions at micro-scale. This difference is believed to originate from thermally induced dynamic ripples in the atomically thin membrane. In this paper, we perform modal analysis to estimate the effective macroscopic bending rigidity of graphene membranes from the frequency spectrum of their Brownian motion. Our method is based on fitting the resonance frequencies obtain…
Hydrogen is one of the prime candidates for clean energy source with high energy density. However, current industrial methods of hydrogen production are difficult to provide hydrogen with high purity, thus hard to meet the requirements in many application scenarios. Consequently, the development of large-scale and low-cost hydrogen separation technology is urgently needed. In this work, the gas separation properties of a newly synthesized two-dimensional nanoporous graphene (NPG) membrane material with patterned dumbbell-shape nanopores are investigated. The permeation energy barriers of diffe…
We report on the development of a pneumatically coupled graphene membrane system, comprising of two circular cavities connected by a narrow trench. Both cavities and the trench are covered by a thin few-layer graphene membrane to form a sealed dumbbell shaped chamber. Local electrodes at the bottom of each cavity allow for actuation of each membrane separately, enabling electrical control and manipulation of the gas flow inside the channel. Using laser interferometry, we measure the displacement of each drum at atmospheric pressure, as a function of the frequency of the electrostatic driving f…
Reverse electrodialysis is a promising method to harvest the osmotic energy stored between seawater and freshwater, but it has been a long-standing challenge to fabricate permselective membranes with the power density surpassing the industry benchmark of 5.0 W $m^{-2}$ for half a century. Herein, we report a vertically-oriented graphene oxide membranes (V-GOMs) with the combination of high ion selectivity and ultrafast ion permeation, whose permeation is three orders of magnitude higher than the extensively studied horizontally stacked GOMs (H-GOMs). By mixing artificial seawater and river wat…
We report on the adsorption dynamics of phospholipid membranes on graphene-coated substrates using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. We compare the lipid vescle interaction and membranne formation on gold and silicon dioxide QCM crystal surfaces with their graphene oxide (GO) and reduced (r)GO coated counterparts, and report on the different lipid structures obtained. We establish graphene derivative coatings as support surfaces with tuneable hydrophobicity for the formation of controllable lipid structures. One structure of interest formed are lipi…
Angstrom confined solvents in two-dimensional laminates travel through interlayer spacings, gaps between adjacent sheets, and via in plane pores. Among these, experimental access to investigate the mass transport through in plane pores is lacking. Here, we create these nanopores in graphene oxide membranes via ion irradiation with precise control over functional groups, pore size and pore density. Low ion induced pore densities result in mild reduction and increased water permeation for the membranes. Higher pore densities lead to pronounced reduction and complete blockage of pure water howeve…
This study investigates the prospect of using reduced graphene oxide encapsulated between thin wood membranes as a composite filter for water filtration. Graphene oxide (GO) with a volume range of 0.2 to 0.5 mL was deposited on a 95 mm2 area of thin sheets of Balsa wood with a thickness range of 2.20 - 3.50 mm. The dried GO deposits were laser treated in reduced oxygen environment to prepare a reduced graphene oxide-wood composite (rGO-wood). The rGO substrate of the composite was sandwiched between 2 wood sheets which were glued using polydimethylsiloxane (PDMS) to give a stable membrane. Fab…
Graphene (GR) remarkable mechanical and electrical properties - such as its Young's modulus, low mass per unit area, natural atomic flatness and electrical conductance - would make it an ideal material for micro and nanoelectromechanical systems (MEMS and NEMS). However, the difficulty of attaching GR to supports coupled with naturally occurring internal defects in a few-layer GR can significantly adversely affect the performance of such devices. Here, we have used a combined contact resonance atomic force microscopy (CR-AFM) and ultrasonic force microscopy (UFM) approach to characterise and m…
Many industrial and agricultural applications require the treatment of water streams containing high concentrations of ionic species for closing material cycles. High concentration factors are often desired, but hard to achieve with established thermal or membrane-based water treatment technologies at low energy consumptions. Capacitive deionization processes are normally assumed as relevant for the treatment of low salinity solutions only. Flow-electrode capacitive deionization (FCDI), on the other hand, is an electrically driven water desalination technology, which allows the continuous desa…
The excellent mechanical properties of graphene have enabled it as appealing candidate in the field of impact protection or protective shield. By considering a monolayer graphene membrane, in this work, we assessed its deformation mechanisms under hypervelocity impact (from 2 to 6 km/s), based on a serial of in silico studies. It is found that the cracks are formed preferentially in the zigzag directions which are consistent with that observed from tensile deformation. Specifically, the boundary condition is found to exert an obvious influence on the stress distribution and transmission during…
Nitrogen doping of the carbon is an important method to improve the performance and durability of catalysts for proton exchange membrane fuel cells by platinum-nitrogen and carbon-nitrogen bonds. This study shows that p-phenyl groups and graphitic N acting bridges linking platinum and the graphene/carbon black (the ratio graphene/carbon black=2/3) hybrid support materials achieved the average size of platinum nanoparticles with (4.88 +/- 1.79) nm. It improved the performance of the lower-temperature hydrogen fuel cell up to 0.934 W cm-2 at 0.60 V, which is 1.55 times greater than that of comme…
