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This study presents an efficient isolation of human lung carcinoma cell line (A549) platform by utilizing the proposal a serpentine microchannel with added cavities (SMAC) platform. The magnetic micro-bead isolation performance in proposed serpentine channel was simulated using COMSOL Multiphysics. The experimental procedures of aptamer molecular conjugation on magnetic microbeads affined to A549 cell line were also reported. The experimental results indicated that at the flow rate of 5 µL/s, the capture rate of human lung carcinoma cell reached above 70% in less than 15 min, whereas non-target cell capture rate was around 1.5%. The proposed platform shows its potential of high selectivity, portable, and simple-to-operate, which are suitable considerations for developing point-of-care applications in various biological and clinical purposes.

This study reports the results on the development of an electrical impedance-based protein detection circuit board for the protein detection biochip. A digital quadrature phase shift module, which can generate two sine waves with 90-degree difference in phase in a large frequency range is employed for lock-in amplifier block for impedance profiling. A microcontroller is used for frequency selection and data acquisition. The measurement module is connected with a computer to display the impedance profile. The implemented board were applied to protein detection biochip to detect the presence of the protein of interest in an essay sample. Experiment is performed for 10 μM Bovine serum albumin (BSA) labeled with fluorescein isothiocyanate (FITC-BSA) protein sample in 10 mM PBS medium solution with the frequency range from 10 kHz to 200 kHz. The measured results reveal a clear impedance change between before and after trapping protein on the microelectrodes of the biochip. The developed electrical impedance spectroscopy board enables rapid and effective protein detection at low concentration.

This paper presents a design of a compact system for low concentration protein detection based on an effectiveness concentrator which is relied on exclusion-enrichment effect (EEE) and a highly sensitivity lock-in impedance measurement technique. Experiment results suggested that protein concentration of down to sub-nanomolar can be detected by the proposed system.

This paper presents a dielectrophoresis (DEP) enrichment microfluidic platform with built-in antibody-based capacitive sensor for tumor rare cells detection. We take the advantages of the effective DEP actuation, the high selectivity property of antibody for rare cell immobilization, and the high sensitivity of differential capacitive sensing for quantitatively reading out, to produce advanced platform, toward single tumor cell detection for the rapid laboratory tests of cancers diagnoses and other metabolic diseases applications.

This paper develops a multi-antibody array biochip for detection of different-grade bladder cancer cell lysates based on protein expression level. Two nanoprobes modified with antibodies, Galectin-1 (Gal-1) and Lactate Dehydrogenase B (LDH-B), were immobilized in an array manner by sequent DEP manipulation steps including focusing, guiding and trapping, therefore, two different protein levels can be achieved in single chip without complex microchannel design. The structure of DEP chip consists of three electrode layers, top electrode made of Indium Tin Oxide (ITO), middle Au electrode on SU-8 surface for focusing and guiding of nanoprobes, and bottom ITO dot electrodes under SU-8 cavity for trapping of nanoprobes. In our experiments, two different grade bladder cancer cell lysates (grade I:RT4 and grade III:T24) were introduced into immunosensor, the expression levels of Gal-1 and LDH-B displayed different fluorescent responses for RT4 and T24 cell lysates. Accordingly, the fluorescence intensity of Gal-1 is higher than the value of LDH-B for T24 cell lysate; however, the response for RT4 is opposite, i.e. LDH-B > Gal-1. Consequently, determining of different-grade bladder cancer cell can be achieved by using present multi-antibody immunosensor. In addition, the DEP manipulations of nanoprobes also demonstrate the feasibility for multi-biomarker array in single chip for point-of-care diagnostics.

Dielectrophoresis (DEP) has been demonstrated the manipulations of bio-modified particles for biosensors, and the microelectrodes are mostly made of metal materials such as Au, Cu and Pt, etc. However, the metal electrodes could induce extra background noise as observed the DEP chip in a fluorescence microscope. Currently, the fluorescence response still dominates the indicators of immunoassays; therefore, it's important to eliminate the extra background noise of fluorescence response form metal electrodes for an immunosensor. In this study, a DEP chip was utilized to immobilize the nanoprobes in a microcavities array for immunosensing. A transparent conductive material, Indium Tin Oxide (ITO), was employed in the fabrication of DEP electrodes, and the fluorescence responses of DEP chip with transparent (ITO) electrodes were compared with identical DEP chip with conventional Au electrodes during immunoassay. According to experimental results, the enhancement of fluorescence response of DEP chip with ITO electrodes was greater than the values of DEP chip with Au electrodes about 1.57 times and 1.44 times for the immunosensing of 10 nM and 1 nM BSA, respectively. In addition, by applying the DEP force during the immunosensing, the fluorescence response was also enhanced due to the BSA can be condensed by DEP force. The DEP condensation was more significant for immunosensing at low BSA concentration. Consequently, we have demonstrated a DEP chip with transparent ITO electrodes and the background noise of fluorescence response can be eliminated to enhance the sensitivity of immunosensing.

The main purpose of this paper was to numerically design an insulator-based dielectrophoretic microdevice with three-dimensional focusing of biological cells. The cells were introduced into the microchannel and pre-confined hydrodynamically by the funnel-shaped insulating structures close to the inlet. The dielectrophoretic force was employed to confine the cells with a negative dielectrophoretic response. The dual-planar electrodes connected to the opposite pole were designed at the top and bottom surfaces of the microchannel. Four insulating structures, which formed an X-pattern as shown in the microchannel, were employed to squeeze the electric field in a conducting solution, thereby generating high-electric-field regions. The results of numerical simulation indicated apparently that the increase of the electric field applied significantly enhanced the performance of focusing. According to the numerical results, decreasing the inlet velocity could increase the efficiency of focusing. The transient simulation of viable cell tracks also demonstrated that the three-dimensional focusing of particles was successfully achieved. The design proposed herein has no need of complicated flow controls for focusing of cells. The microdevice is easy to operate and integrate into further biomedical applications.

Bio-molecular recognition is detected by the unique optical properties of self-assembled gold nanoparticles on the unclad portions of an optical fiber whose surfaces are modified with a receptor. To enhance the performance of the sensing platform, the sensing element is integrated with microfluidic chips to reduce sample and reagent volume, to shorten response time and analysis time, as well as to increase sensitivity. The main purpose of the present study is to design grooves on the optical fiber for FO-LPR microfluidic chip and investigate the effects of the groove geometry on the biochemical binding kinetics. The optical fiber is designed and termed as U-type or D-type based on the shape of grooves. The numerical results indicated that the design of the D-type fiber exhibits efficient performance on biochemical binding. The grooves designed on the optical fiber could also induce chaotic advection to enhance the mixing in the microchannel. The mixing patterns indicate that the D-type grooves enhance the mixing more effectively than U-type grooves. The D-type fiber with six grooves is an optimum design according to the numerical results.

Hyperthermia affects certain regulatory proteins, kinases or cyclins, resulting in alternations to the cell cycle and even to apoptosis. Damage to the cell plasma membrane is a key factor in the killing of a cell by hyperthermia. Analysis at the single-cell level is necessary for understanding the fundamental mechanisms of hyperthermia-induced cell death and the generation of thermotolerance in surviving cells. The main purpose of this study is to fabricate a hydrogel chip with microwells for cellular patterning and to demonstrate the measurement of supraphysiological thermal injury in human carcinoma cells (HeLa cells) at the single-cell level. To accomplish this, measurement of membrane injury by dye leakage post-thermal insult was performed and reported in this work. For cell concentrations at 0.5×10 cells/mL, the occupancy of cells on the microchip with 40 μm microwells was up to 86.6%, a value far higher than that found on the 30 μm microwells (approximately 78.5%). The fluorescent images showed that calcein leakage occurred when cell membranes were damaged under supraphysiological temperatures between 43 and 50°C. The single-cell-based experiment of thermal injury in the microchip with hydrogel microwells was therefore successfully demonstrated.

Current clinical methods for the separation of whole blood into blood cells and cell-free plasma are currently based on large facility equipment. The disadvantage of this process is that the patients must have assays performed at the hospital where the separation facility is located. The present study presents a design for microfluidic chips with different microchannel structures, which utilizes backward facing step geometry and centrifugal force to extract the cell-free plasma from whole blood samples at the branch of the microchannel for further assay, avoiding the influence of blood cells. Numerical simulation was performed on a personal computer to analyze the effects of inlet velocity and the structures of the microchannel on the flow field and back-flow in the microchannel, as well as the efficiency of separation and the volumetric fraction of the flowrate of plasma extraction. Based on the numerical simulations, the design with both converging and bending channels was the best design among the two layouts proposed. The experimental results agreed with the numerical predictions well in the present study.

For medical applications of cell sorting, counting or flow cytometry, focusing of biological cells in microdevices is a prerequisite. Hydrodynamic focusing by sheath flow has been a widely used method for particle focusing, however, additional buffer inlets and precise flow control were needed. An insulator-based dielectrophoretic microdevice of four insulating structures forming X-pattern with effective focusing of biological cells was designed in this paper. The effects parameters such as electric filed applied and inlet velocity were also investigated herein. The inlet flow field and the electric field were applied vertically. The cells were introduced into the microchannel and pre-confined hydrodynamically by the funnel-shaped insulating structures close to the inlet. Thereupon the cells flowed into the constricting region where the square of the electric field distributed as saddle-shaped. The cells with negative dielectrophoretic response were therefore repelled toward the center of the constricting region. It indicated apparently that the increase of the electric field applied significantly enhanced the performance of focusing. According to the numerical results, decreasing the inlet velocity could increase the efficiency of focusing. The design proposed herein has no need of complicated flow controls for focusing of cells. The microdevice is easy to operate and integrate into further biomedical applications.

The realization of the biosensing platform could be achieved via the measurement of evanescent wave absorption by the nanoparticle-modified optical fiber. The present microfluidic device was made of polymethylmethacrylate (PMMA) by microinjection molding. The reaction microchannel is 950µm high and 950µm wide with an effective binding length of 18.1 mm. An unclad optical fiber of 400µm in diameter, which was is fixed at the center of the microchannel. A gold nanoparticles monolayer was coated on the unclad portion of the optical fiber. Therefore, receptors were modified on the colloidal gold surface to functionalize the gold surface. The present study was to simulate the biochemical assays in the fiber-optic localized plasma resonance (FO-LPR) microfluidic chip, and to investigate the effects parameters such as inlet concentrations of analyte or the flowrate on the biochemical binding kinetics. The numerical investigation was helpful for the optimization of designing the FO-LPR microfluidic chip.

Depending on the duration of exposure at supraphysiological temperatures, cellular proteins and organelles would suffer structural alternation and irreversible denaturation which may induce cell death. In the present study, a commercial hotplate was used to provide a constant temperature to heat the human embryonic kidney cells (293 T). Heat transfer model were performed to evaluate thermal equilibrium time required for the cell samples. The survival of the human embryonic kidney cell line was investigated herein and the frequency factor and activation energy of 293 T cells in the Arrhenius model for the thermal induced cell injury were obtained as A = 5.95x1030 s-1~ and DeltaE=211.79 kJ/mol, respectively. It can also be observed patently that the cell membrane was ruptured when the cell was exposing such a supraphysiological temperature.

The ability to manipulate particles, especially living cells, is fundamental needed to many biological and medical applications, including isolation and detection of sparse cancer cells, concentration of cells from dilute suspensions, separation of cells according to specific properties, and trapping and positioning of individual cells for characterization. The electrodeless dielectrophoretic (EDEP) trapping is composed of conductless tetragon structures in micro-chip. We have improved the design of EDEP geometries, correlated particle acted by DEP effects with electrical-field distributions determined through insulating microstructures produce non-uniform electric fields to drive particles in microsystems. This study is attempt to research on microfluidic trapping by using DEP force and to investigate the relation on important parameters of microchip device for our design to comprehend the factors containing the spacing between two structures, the applied voltage and flow velocity.

The melting duration and molten depth are key information for laser-assisted direct imprinting, which raises issues about the melting & solidification induced by excimer-pulse-laser irradiating through unilaterally transparent binary materials. Considering the size-effect on thermal conductivity and phase-change of irradiated material, the thermal-contact resistance is taken into account to simulate and predict the melting behavior for this process. Results in this study indicate that the laser-annealing case as well as the perfect-contact case provides the upper-bound and the lower-bound values for the physical quantities involved in this process even without the detail information of the changing values of thermal-contact resistance

Gold nanoparticles modified with 21-based thiolated-oligonucleotides have been utilized as novel gene delivery vehicles for electroporation on microchips in the present study. The electroporation chip, consisting of a defined cell culture cavity region with thin film electrodes made of titanium and gold, was fabricated on a glass slide using microfabrication technologies. The electric field for the Au-DNA conjugates attracting was generated to induce the electrophoresis of Au-DNA conjugates and enhance the transfection efficient on the electroporation microchip. Both the UV-vis spectra of the surface plasmon resonance and TEM micrographs indicated that the nanoparticles associated with DNA could be delivered into cells utilizing electroporation. This investigation had demonstrated the nanoparticle-based gene delivery system.

A bi-directional microfluid control system was developed both numerically and experimentally in this work. This pneumatic system is an on-chip planar structure without moving parts and does not require microfabricated heaters or electrodes. The pumping actuation is introduced to the microchannel fabricated in-chip by blowing an airflow through the device. The tunable parameters for adjusting the performance of pumping were the location of the inlet channel and the velocity of the airflow. The driving module was fabricated on PMMA and its feasibility was examined experimentally. A droplet of water in the microchannel can move forward, backward and stop under control of the driving module. The driving system is therefore particularly suited to micro devices for biochemical analysis.