Sensor for Continuous and Real-Time Monitoring of Biomolecule Permeation Through Ultrathin Silicon Nanoporous Membranes
TL;DR: In this paper, the authors used ultrathin silicon nanoporous membranes (SNMs) combined with detection using ultraviolet absorption for continuous and real-time monitoring of biomolecules.
Abstract: The increase in demand for continuous and real-time monitoring of permeation of biomolecules is addressed by using highly selective ultrathin silicon nanoporous membranes (SNMs) combined with detection using ultraviolet absorption. The membranes, with an average pore size of 8.8 nm, are fabricated using semiconductor batch processes including chemical vapor deposition and rapid thermal annealing. Bovine serum albumin (BSA) of a concentration of $250~\mu \text{g}$ /ml is used as the test molecule. The concentration of BSA diffused through the membrane is measured using optical transduction based in-house developed sensor. The photocurrent obtained from the sensor is measured every 15 min and compared with the standard Bradford assay at the same time-stamp. The concentration estimated by the sensor is found to agree with the Bradford assay with a standard deviation of 1.4%. The throughput of the membrane is increased by fabricating an array of SNMs, which showed an increase in diffusion rate by 3.8 times with respect to the single SNM. The clogging of pores by the biomolecules is analyzed using ionic conductivity experiments. The structural integrity of BSA diffused through the SNM is also analyzed.
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TL;DR: Porous silicon membranes (PSiMs) have been extensively studied in the literature as mentioned in this paper, with the emphasis on the integration challenges that PSiMs are facing for future industrialization.
Abstract: Porous silicon (PSi) research has been active for several decades. The multiple properties and structural features of PSi have made it a promising material for a wide variety of applications, going from drug delivery to microelectronics. By removing the bulk silicon below a PSi layer and creating a membrane, a whole new set of physical and chemical characteristics as well as potential uses have been discovered. In this review, recent works on Porous silicon membranes (PSiMs) are analysed and summarised. An updated overview of the progress made in several areas is presented with the purpose of highlighting PSiM's potential. New methods for the fabrication and the integration of PSiMs have been developed, relying more and more on semiconductors microfabrication techniques. Likewise, the properties of PSiMs have been extensively studied, enabling the emergence of a multitude of PSiM-based systems. A critical analysis of the advantages and disadvantages of this material is made, with the emphasis on the integration challenges that PSiMs are facing for future industrialisation.
17 citations
01 Jun 2021
TL;DR: In this article, the influence of different process parameters on the deposition rate of the silicon oxide film that influence properties like the refractive index and the post-deposition etch rate was investigated.
Abstract: Ultrathin silicon nanoporous membrane, with applications in biomolecular separation, can be fabricated by rapid thermal annealing of a 15-nm-thick amorphous silicon film sandwiched between two thin silicon oxide capping layers. Here, we investigated the influence of different process parameters on the deposition rate of the silicon oxide film that influence properties like the refractive index and the post-deposition etch rate. The improvement in the oxide film quality, brought about by reducing the ICP power while simultaneously increasing RF power, results in an eight fold reduction in the etch rate of the deposited layer. This allows for the deposition of thinner oxide capping layers and the resulting reduced thermal mass induces pore formation at lower annealing temperatures facilitating greater variation in pore sizes and porosities of the membrane.
1 citations
TL;DR: In this paper , the practical use of polarimetric sensing on n-type porous silicon and porous alumina freestanding membranes (Whatman-anodic membranes with pore widths of 200 nm and thickness of 60 μm) is investigated for both in-plane and out-of-plane birefringence.
20 Jul 2021
TL;DR: Density functional theory calculations have been made to investigate the adsorption and sensing properties of harmful nitrogen oxides (NO, NO2) on rhodium (Rh) doped hexagonal boron nitride (BN) to explore the feasibility of Rh-doped BN (Rh-BN) based gas sensor.
Abstract:
Density functional theory calculations have been made to investigated the adsorption and sensing properties of harmful nitrogen oxides (NO, NO2) on rhodium (Rh) doped hexagonal boron nitride (BN) to explore the feasibility of Rh-doped BN (Rh-BN) based gas sensor. For each gas molecule, various adsorption positions and orientations were examined. The favorable adsorption configuration has been established and the corresponding adsorption energy has been calculated. Besides, to understand the adsorption mechanism, The properties such as electron density, the energy band structure, state density of states, and charge transfer of the adsorption system were investigated in greater detail. The calculations indicate that the most stable structure is that the Rh atom located directly above the N atom, and a stable chemical bond with a length of 2.096 Å formed between the Rh atom and N atom, with a significant binding energy (𝐸𝑏) of -1.561 eV. Then, adsorption performance of Rh-BN monolayer upon nitrogen oxides is in order as NO2 > NO, with the adsorption energy (𝐸𝑎) of -3.919 eV and -3.318 eV, respectively. This indicates that the Rh-BN single layer possesses ideal adsorption and sensing properties. Furthermore, by doping the Rh atom, many levels of impurities are introduced into the intrinsic BN band structure, thereby improving the interaction between BN and adsorbed gas molecules. Following adsorption of NO and NO2, the band gap (Eg) of the doping system is wider. It has been demonstrated that gas adsorption reduces the electrical conductivity of the system, but increases the sensitivity of the system. The above calculation and analysis are of great importance for the exploration of the Rh-BN single layer as innovative gas detection material.
References
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Book•
16 Dec 1999
TL;DR: Overview of membrane science and technology membrane transport theory membrane and modules concentration polarization reverse osmosis ultrafiltration microfiltration gas separation pervaporation ion exchange membrane processes - electrodialysis carrier facilitated transport medical applications of membranes other membranes processed.
Abstract: Overview of membrane science and technology membrane transport theory membrane and modules concentration polarization reverse osmosis ultrafiltration microfiltration gas separation pervaporation ion exchange membrane processes - electrodialysis carrier facilitated transport medical applications of membranes other membranes processed.
3,680 citations
"Sensor for Continuous and Real-Time..." refers methods in this paper
...An efficient method to separate biomolecules from a mixture is to use porous membranes [9]....
[...]
TL;DR: A comprehensive overview on the development of polymeric membranes having advanced or novel functions in the various membrane sepn processes for liq. and gaseous mixts can be found in this paper.
1,841 citations
"Sensor for Continuous and Real-Time..." refers background in this paper
...Though organic membranes attracted commercial interest due to their low-cost and high mechanical strength, its chemical and thermal instability and longer pore lengths hindering the free flow of biomolecules resulted in the development of inorganic membranes [26]–[28]....
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TL;DR: A rapid and accurate method for the estimation of protein concentration is essential in many fields of protein study, but is susceptible to interference from a wide range of compounds commonly present in biological extracts.
Abstract: A rapid and accurate method for the estimation of protein concentration is essential in many fields of protein study. The Lowry method ( Chapter 1 in vol. 1 of this series) has been widely used, but is susceptible to interference from a wide range of compounds commonly present in biological extracts. Although interference can be avoided by trichloracetic acid precipitation of the protein prior to assay, this lengthens the procedure.
1,573 citations
"Sensor for Continuous and Real-Time..." refers methods in this paper
...solution in trans tube is taken out to be assayed using Bradford assay for proteins [60] at the same time-stamp....
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TL;DR: In this article, self-organized hexagonal pore arrays with a 50-420 nm interpore distance in anodic alumina have been obtained by anodizing aluminum in oxalic, sulfuric, and phosphoric acid solutions.
Abstract: Self-organized hexagonal pore arrays with a 50–420 nm interpore distance in anodic alumina have been obtained by anodizing aluminum in oxalic, sulfuric, and phosphoric acid solutions. Hexagonally ordered pore arrays with distances as large as 420 nm were obtained under a constant anodic potential in phosphoric acid. By comparison of the ordered pore formation in the three types of electrolyte, it was found that the ordered pore arrays show a polycrystalline structure of a few micrometers in size. The interpore distance increases linearly with anodic potential, and the relationship obtained from disordered porous anodic alumina also fits for periodic pore arrangements. The best ordered periodic arrangements are observed when the volume expansion of the aluminum during oxidation is about 1.4 which is independent of the electrolyte. The formation mechanism of ordered arrays is consistent with a previously proposed mechanical stress model, i.e., the repulsive forces between neighboring pores at the metal/oxide interface promote the formation of hexagonally ordered pores during the oxidation process.
1,496 citations
"Sensor for Continuous and Real-Time..." refers background in this paper
...dation [29], [30], focused ion beam (FIB) drilling [31]–[33], lithography [34]–[36], electrochemical etching [37] and rapid thermal annealing (RTA) [38]–[42]....
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TL;DR: A new technique for fabricating silicon oxide nanopores with single-nanometre precision and direct visual feedback, using state-of-the-art silicon technology and transmission electron microscopy is reported.
Abstract: Single nanometre-sized pores (nanopores) embedded in an insulating membrane are an exciting new class of nanosensors for rapid electrical detection and characterization of biomolecules. Notable examples include α-hemolysin protein nanopores in lipid membranes1,2 and solid-state nanopores3 in Si3N4. Here we report a new technique for fabricating silicon oxide nanopores with single-nanometre precision and direct visual feedback, using state-of-the-art silicon technology and transmission electron microscopy. First, a pore of 20 nm is opened in a silicon membrane by using electron-beam lithography and anisotropic etching. After thermal oxidation, the pore can be reduced to a single-nanometre when it is exposed to a high-energy electron beam. This fluidizes the silicon oxide leading to a shrinking of the small hole due to surface tension. When the electron beam is switched off, the material quenches and retains its shape. This technique dramatically increases the level of control in the fabrication of a wide range of nanodevices.
1,375 citations