Biofunctionalized all-polymer photonic lab on a chip with integrated solid-state light emitter

A photonic lab on a chip(PhLOC),comprising a solid-state light emitter(SSLE)aligned with a biofunctionalized optofluidic multiple internal reflection(MIR)system,is presented.The SSLE is obtained by filling a microfluidic structure with a phenyltrimethoxysilane(PhTMOS)aqueous sol solution containing a fluorophore organic dye.After curing,the resulting xerogel solid structure retains the emitting properties of the fluorophore,which is evenly distributed in the xerogel matrix.Photostability studies demonstrate that after a total dose(at λ5365 nm)greater than 24 J cm^(-2),the xerogel emission decay is only 4.1%.To re-direct the emitted light,the SSLE includes two sets of air mirrors that surround the xerogel.Emission mapping of the SSLE demonstrates that alignment variations of 150 mm(between the SSLE and the external pumping light source)provide fluctuations in emitted light smaller than 5%.After this verification,the SSLE is monolithically implemented with a MIR,forming the PhLOC.Its performance is assessed by measuring quinolone yellow,obtaining a limit of detection(LOD)of(0.6060.01)mM.Finally,the MIR is selectively biofunctionalized with horseradish peroxidase(HRP)for the detection of hydrogen peroxide(H_(2)O_(2))target analyte,obtaining a LOD of(0.760.1)μM for H_(2)O_(2),confirming,for the first time,that solid-state xerogel-based emitters can be massively implemented in biofunctionalized PhLOCs.

Applied Study on Magnetic Nanometer Beads in Preparation of Genechip Samples

A protocol for enrichment and adsorption of karyocyte from whole blood by using magnetic nanometer beads as solid phase absorbents was presented. The PCR amplification could be accomplished by using the nanobeads with karyocyte as template directly and the PCR products were applied on an oligonucleotide array to do gene typing. The HLA A PCR amplification system and a small HLA A oligonucleotide microarray were applied as the platform and an experiment protocol of separating karyocyte from whole blood using the magnetic nanometer beads (Fe 2O 3) were set up. The experimental conditions were also discussed. It showed that pH level of PBS eluent, Taq enzyme quantity and fragment length of products could influent the amplification results, and the magnetic nano beads could succeed in sample preparation in microarray to provide a promising way in automatic detection and lab on a chip.

Toward integrated detection and graphene-based removal of contaminants in a lab-on-a-chip platform

A novel miniaturized microfluidic platform was developed for the simultaneous detection and removal of polybrominated diphenyl ethers （PBDEs）. The platform consists of a polydimethylsiloxane （PDMS） microfluidic chip for an immunoreaction step, a PDMS chip with an integrated screen-printed electrode （SPCE） for detection, and a PDMS-reduced graphene oxide （rGO） chip for physical adsorption and subsequent removal of PBDE residues. The detection was based on competitive immunoassay-linked binding between PBDE and PBDE modified with horseradish peroxidase （HRP-PBDE） followed by the monitoring of enzymatic oxidation of o-aminophenol （o-AP） using square wave anodic stripping voltammetry （SW-ASV）. PBDE was detected with good sensitivity and a limit of detection similar to that obtained with a commercial colorimetric test （0.018 ppb）, but with the advantage of using lower reagent volumes and a reduced analysis time. The use of microfluidic chips also provides improved linearity and a better reproducibility in comparison to those obtained with batch-based measurements using screen-printed electrodes. In order to design a detection system suitable for toxic compounds such as PBDEs, a reduced graphene oxide-PDMS composite was developed and optimized to obtain increased adsorption （based on both the hydrophobicity and rr-v~ stacking between rGO and PBDE molecules） compared to those of non-modified PDMS. To the best of our knowledge, this is the first demonstration of electrochemical detection of flame retardants and a novel application of the rGO-PDMS composite in a biosensing system. This system can be easily applied to detect any analyte using the appropriate immunoassay and it supports operation in complex matrices such as seawater.

Nanotechnology:fundamental research to product development

The concept of an integrated "lab on a chip" has long been a goal for the micro-electro-mechanical-systems(MEMS) community.This would entail the integration of not only the sampling and analysis of various functions,but also the ability to transmit this information off the chip to a central repository.This paper describes the initial steps in the fabrication of a "lab on a chip" which would continually analyze blood sampled via microneedles using techniques such as nano plasmonics,specifically,concentrations of glucose.The analysis could then be transmitted off the chip using digital signal processing.This paper describes the analysis and optimization of the microneedle shape and size and the fabrication of the resulting needles in silicon using deep reactive ion etching(DRIE).The paper also describes the opportunities for fabrication of such needles in alternative materials and describes the issues that still have to be overcome before such an integrated device is realized.

On-chip 3D rotation of oocyte based on a vibration-induced local whirling flow

We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the micropillars.The direction and velocity of this flow can be controlled by changing the direction and amplitude of the applied vibration.Furthermore,this flow can be induced on an open chip structure.In this study,we adopted a microchip with three micropillars arranged in a triangular configuration and an xyz piezoelectric actuator to apply the circular vibration.At the centre of the micropillars,the interference of the vibration-induced flows originating from the individual micropillars induces rotational flow.Consequently,a biological cell placed at this centre rotates under the influence of the flow.Under three-plane circular vibrations in the xy,xz or yz plane,the cell can rotate in both the focal and vertical planes of the microscope.Applying this 3D cell rotation method,we measured the rotational speeds of mouse oocytes in the focal and vertical planes as 63.7±4.0°s^(−1) and 3.5±2.1°s^(−1),respectively.Furthermore,we demonstrated the transportation and rotation of the mouse oocytes and re-positioned their nuclei into a position observable by microscope.

Applications of biosensors for bacteria and virus detection in food and water–A systematic review

Biosensors for sensitive and specific detection of foodborne and waterborne pathogens are particularly valued for their portability,usability,relatively low cost,and real-time or near real-time response.Their application is widespread in several domains,including environmental monitoring.The main limitation of currently developed biosensors is a lack of sensitivity and specificity in complex matrices.Due to increased interest in biosensor development,we conducted a systematic review,complying with the PRISMA guidelines,covering the period from January 2010 to December 2019.The review is focused on biosensor applications in the identification of foodborne and waterborne microorganisms based on research articles identified in the Pubmed,Science Direct,and Scopus search engines.Efforts are still in progress to overcome detection limitations and to provide a rapid detection system which will safeguard water and food quality.The use of biosensors is an essential tool with applicability in the evaluation and monitoring of the environment and food,with great impact in public health.

Low-cost and versatile integration of microwire electrodes and optical waveguides into silicone elastomeric devices using modified xurographic methods

Microelectrodes are used in microfluidic devices for a variety of purposes such as heating,applying electric fields,and electrochemical sensing.However,they are still manufactured by expensive deposition techniques such as sputtering or evaporation and patterned using photolithography methods.More recently,alternate methods including nanoparticle sintering and use of liquid metal flowing through microchannels have been used to fabricate microelectrodes.These methods are limited in the material choices or require post processing to be integrated into microchannels.Here we developed a low-cost and versatile method to integrate high-quality metal microwires into polydimethylsiloxane(PDMS)using xurography.The microwire integration process includes cutting slit pattern on PDMS substrate and subsequent writing metal microwires into the slit pattern using a specialized tip.Then the microwire-integrated PDMS was sealed/bonded using uncured PDMS prepolymer.This method enables integration of metal microwires of diameter as small as 15μm into PDMS devices.Integration of multiple microwires with minimum spacing of 150μm has also been demonstrated.The versatility of this method is demonstrated by the fabrication of metal microwire suspended in the middle of the microchannel,which is difficult to achieve using conventional electrode fabrication methods.This low-cost method avoids expensive clean room fabrication yet producing high-quality electrodes and can be used in a variety of microfluidic and MEMS applications.