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Thin-core fiber-optic biosensor for DNA hybridization detection
摘要： A real-time label-free DNA biosensor based on thin-core fiber (TCF) interferometer is demonstrated experimentally. The proposed biosensor is constructed by splicing a TCF between two segments of single mode fibers (SMFs) and integrated into a microfluidic channel. By modifying the TCF surface with monolayer poly-l-lysine (PLL) and single-stranded deoxyribonucleic acid (ssDNA) probes, the target DNA molecules can be captured in the microfluidic channel. The transmission spectra of the biosensor are measured and theoretically analyzed under different biosensing reaction processes. The results show that the wavelength has a blue-shift with the process of the DNA hybridization. Due to the advantages of low cost, simple operation as well as good detection effect on DNA molecules hybridization, the proposed biosensor has great application prospects in the fields of gene sequencing, medical diagnosis, cancer detection and environmental engineering.
关键词： thin-core fiber,biosensor,microfluidic channel,modal interference,DNA hybridization
更新于2025-11-28 14:23:57
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A microfluidic all-vanadium photoelectrochemical cell with the N-doped TiO2 photoanode for enhancing the solar energy storage
摘要： In this work, the nitrogen-doped TiO2 photocatalyst is synthesized and applied in a microfluidic all-vanadium photoelectrochemical cell for enhancing the solar energy storage. The use of the nitrogen-doped TiO2 photoanode and the minimization design can ensure the visible-light response, increased specific surface area, vigorous pore structure and enhanced photon and mass transport as well as more uniform light distribution. Various characterizations are performed to evaluate the developed photocatalyst and microfluidic all-vanadium photoelectrochemical cell. The results confirm that the developed nitrogen-doped TiO2 photoanode can provide both the extended absorption spectrum and the small anatase crystal size as well as the obviously enlarged specific surface area with plentiful pore structure. Because of these merits, the microfluidic all-vanadium photoelectrochemical cell with the nitrogen-doped TiO2 photoanode yield the average photocurrent density of 0.103 mA/cm2 during the long-term operation, which is much higher than those with the un-doped TiO2 photoanode (0.086 mA/cm2) and commercial P25 TiO2 photoanode (0.073 mA/cm2), presenting 19.8% and 41% improvements, respectively. The results demonstrate not only the promotion of the vanadium reversible redox pairs conversion but also the inherently excellent stability by the nitrogen-doped TiO2 photoanode.
关键词： Photoanode,N-doped TiO2 photocatalyst,Conversion rate,Microfluidic all-vanadium photoelectrochemical cell,Solar energy storage
更新于2025-11-14 17:03:37
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Dynamic fluorescent imaging analysis of mitochondrial redox in single cells with a microfluidic device
摘要： The redox balance in celluar mitochondria is closely related to the physiological and pathological processes of the body. When exposed to external stimuli, the redox state in cells changes dynamically, and presents cell heterogeneity, which creates a need for techniques that can make dynamic and reversible visual analysis of redox in mitochondria at single-cell level. Here we describe a method for single-cell redox analysis based on a microfluidic device combing with a reversible fluorescent probe (Cy-O-ebselen) , that enables online culture, labelling and dynamic fluorescent imaging analysis of mitochondrial redox (H2O2/GSH) change. Using this method, we further explored the dynamic changes of mitochondrial redox state after thermal stimulation or combined thermal-drug stimulation, and analyzed the heterogeneous response of cells to external stimuli at the single cell level.
关键词： single cell,fluorescence,microfluidic,mitochondrial redox
更新于2025-09-23 15:23:52
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Digital LAMP on a Commercial Membrane
摘要： In this work, we report digital loop-mediated isothermal amplification (LAMP) or reverse-transcription LAMP (RT-LAMP) on a commercial membrane, without the need for complex chip fabrication or use of specialized equipment. Due to the pore size distribution, the theoretical error for digital LAMP on these membranes was analyzed, using a combination of Random Distribution Model and Multi-volume Theory. A facile peel-off process was developed for effective droplets formation on the commercial track-etched polycarbonate (PCTE) membrane. Each pore functions as an individual nanoreactor for single DNA amplification. Absolute quantification of bacteria genomic DNA was realized with a dynamic range from 11 to 1.1 × 10^5 copies/μL. One-step digital RT-LAMP was also successfully performed on the membrane for the quantification of MS2 virus in wastewater. With the introduction of new probes, the positive pores can be easily distinguished from negative ones with 100 times difference in fluorescence intensities. Finally, the cost of a disposable membrane is less than $0.1/piece, which, to the best of our knowledge, is the most inexpensive way to perform digital LAMP. The membrane system offers opportunities for point-of-care users or common laboratories to perform digital quantification, single cell analysis, or other bioassays in an inexpensive, flexible and simplified way.
关键词： Digital LAMP,RT-LAMP,PCR,Droplets,Virus,Microfluidic,Membrane,Nucleic acid
更新于2025-09-23 15:23:52
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Nanofluidic and monolithic environmental cells for cryogenic microscopy
摘要： We present a device capable of combining nanofluidics and cryogenic transmission electron microscopy (cryo-TEM) to allow inspection of water-soluble samples under near-native conditions. The devices can be produced in a multitude of designs, but as a general rule, they consist of channels or chambers enclosed between two electron-transparent silicon nitride windows. With the appropriate design, those devices can allow screening of multiple samples in parallel and remove the interaction between the sample and the environment (no air–water interface). We demonstrate channel sizes from 80 to 500 nm in height and widths from 100 to 2000 μm. The presented fabrication flow allows producing hollow devices on a single wafer eliminating the need of aligning or bonding two half-cavities from separate wafers, which provides additional resistance to thermal stress. Taking advantage of a single-step through-membrane exposure with a 100 keV electron beam, we introduced arrays of thin (10–15 nm) electron-transparent silicon nitride membrane windows aligned between top and bottom (200–250 nm) carrier membranes. Importantly, the final devices are compatible with standard TEM holders. Furthermore, they are compatible with rapid freezing of samples, which is crucial for the formation of vitreous water, hence avoiding the formation of crystalline ice, that is detrimental for TEM imaging. To demonstrate the potential of this technology, we tested those devices in imaging experiments verifying their applicability for cryo-TEM applications and proved that vitreous water could be prepared through conventional plunge freezing of the chips.
关键词： nanofabrication,TEM,environmental chamber,microfluidic cell,electron beam lithography,cryo-TEM
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Cell Detection in Microfluidic System by Terahertz Technique
摘要： In this research, a microfluidic system combined with terahertz technique is designed and used for cell detection. Terahertz wave signal, generated by photoconductive antenna, penetrates through cells, medium, and the materials of the microfluidic device. The reflective terahertz signal can be collected by detector and transformed into frequency domain signals. By comparing these signals, this would help us to find out the characteristic signal of material at certain frequency on the order of terahertz range. Furthermore, cells and medium are injected into the microfluidic device. The experiment results demonstrate the capability to differentiate various kinds of material. In the future, this approach can help us to distinguish the cancer cells among normal cells.
关键词： terahertz,microfluidic,Polyscanner-FL7,cell imaging
更新于2025-09-23 15:23:52
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Ultrasensitive and simultaneous detection of two cytokines secreted by single cell in microfluidic droplets via magnetic-field amplified SERS
摘要： A surface-enhanced Raman scattering (SERS)-microfluidic droplet platform for the rapid, ultrasensitive and simultaneous detection of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) secreted by a single cell is presented. The high throughput water-in-oil droplets containing individual cell along with four kinds of immune-particles (antibody-conjugated silver nanoparticles or magnetic beads, AgNPs@Ab1 and MNs@Ab2) in each were achieved by a cross-typed microfluidic chip, and then they were captured by a collection channel array for SERS measurements. In the appearance of cytokines secreted by one cell, AgNPs@Ab1 can be linked onto the surface of MNs@Ab2 through the immune-recognition to form an immune-sandwich, which makes the 'turn on' SERS signal of the Raman reporters previously laid on the surface of MNs due to the adjacent AgNPs. Furthermore, the second SERS signal amplification is from the magnetic field-induced spontaneous collection effect, which brings 75 times enhancement for SERS signal. Additionally, the encapsulation of cytokines in an isolated droplet permits an accumulation effect of targets with time. Owing to the dual signal enhancement and the accumulation effect, such few cytokines secreted by single cell become detectable and a limit of detection is achieved as 1.0 fg/mL in one droplet. By using this ultrasensitive SERS-microdroplet method, the VEGF and IL-8 secretions from several cells in one droplet were explored and the data show that the cell–cell interactions may promote angiogenesis of cancer cells through the up-regulation of VEGF and IL-8.
关键词： surface-enhanced Raman scattering,VEGF,magnetic field amplification,single-cell analysis,IL-8,cytokines,microfluidic droplets
更新于2025-09-23 15:23:52
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AIP Conference Proceedings [Author(s) 4TH ELECTRONIC AND GREEN MATERIALS INTERNATIONAL CONFERENCE 2018 (EGM 2018) - Bandung, Indonesia (27–28 July 2018)] - Multichannel PDMS microfluidic based nano-biolab-on-a-chip for medical diagnostics
摘要： Multichannel PDMS microfluidic based nano-biolab-on-a-chip for medical diagnostics
关键词： medical diagnostics,PDMS,microfluidic,nano-biolab-on-a-chip
更新于2025-09-23 15:23:52
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Microfluidic Sensors with Impregnated Fluorophores for Simultaneous Imaging of Spatial Structure and Chemical Oxygen Gradients
摘要： Interior surfaces of polystyrene microfluidic structures were impregnated with the oxygen sensing dye Pt(II) tetra(pentafluorophenyl)porphyrin (PtTFPP) using a solvent-induced fluorophore impregnation (SIFI) method. Using this technique, microfluidic oxygen sensors are obtained that enable simultaneous imaging of both chemical oxygen gradients and the physical structure of the microfluidic interior. A gentle method of fluorophore impregnation using acetonitrile solutions of PtTFPP at 50oC was developed leading to a 10-μm-deep region containing fluorophore. This region is localized at the surface to sense oxygen in the interior fluid during use. Regions of the device that do not contact the interior fluid pathways lack fluorophores and are dark in fluorescent imaging. The technique was demonstrated on straight microchannel and pore network devices, the latter having pillars of 300 μm diameter spaced center to center at 340 μm providing pore throats of 40 μm. Sensing within channels or pores, and imaging across the pore network devices were performed using a Lambert LIFA-P frequency domain fluorescence lifetime imaging system on a Leica microscope platform. Calibrations of different devices prepared by the SIFI method were indistinguishable. Gradient imaging showed fluorescent regions corresponding to the fluid pore network, dark pillars, and fluorescent lifetime varying across the gradient, thus providing both physical and chemical imaging. More generally, the SIFI technique can impregnate the interior surfaces of other polystyrene containers, such as cuvettes or cell and tissue culture containers, to enable sensing of interior conditions.
关键词： Oxygen,sensor,impregnation,fluorophore,chemical imaging,pore network,polystyrene,microfluidic
更新于2025-09-23 15:22:29
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Fluorescence detection test by black printed circuit board based microfluidic channel for polymerase chain reaction
摘要： This paper proposes the optimal structure of a PCB-based micro PCR chip constructed on a PCB substrate using commercial adhesive tapes and plastic covers. The solder mask of the PCB substrate was coated black, and the area where the reaction chamber is attached was legend printed with white silk to minimize the noise during fluorescence detection. The performance of the PCR and fluorescence detection was compared using 6 types of reaction chambers, each made with different double-sided tapes. Three of the chambers were unsuccessful in completing the PCR. The performance of the other three chambers that successfully amplified DNA was compared using Taqman probe for Chlamydia Trachomatis DNA. The amplified product was illuminated diagonally with a blue LED to excite the product just before imaging, and the LED was turned off when the image was captured to prevent quenching of the probe. The images were taken 10 seconds prior to the last extension step for each cycle using a DSLR camera. The experiments were run as a quartet for each three chambers made with different double-sided tape. The results showed that there were significant difference between the three tapes.
关键词： microfluidic channel,polymerase chain reaction,fluorescence detection test,acrylic adhesive,micro-PCR chip,black PCB,double-sided tape
更新于2025-09-23 15:22:29