Search

One of the most important challenges in the field of microfluidics is the rapid fabrication of microchips with complex topologies. Although the processing method of microfluidic chips has made brilliant achievements in the past 20 years, almost all traditional processing methods still face huge obstacles in the production of complex topologies and three-dimensional microchannel. Nowadays, the main methods of manufacturing microfluidic chips such as numerical control microprocessing, laser ablation, inkjet printing, photolithography, dry etching, and lithography, galvanoformung and abformung (LIGA) technology are not only inapplicable to the complex topological structure and the rapid processing of three-dimensional microfluidic chips but also rely on expensive processing equipment, complex manufacturing process, and low yield. To solve the problems of these traditional processing methods, we propose a low-cost methodology to obtain a microfluidic chip by sewing the chip pipe to the substrate with an embroidery machine as low as $6. Compared with the above-mentioned traditional microprocessing technologies, the new chip processing technology proposed by us does not involve professional microprocessing equipment and professional skills. Therefore, this new chip processing technology can significantly improve the efficiency of microprocessing.

We report a novel compressed air-driven continuous-flow digital PCR (dPCR) system based on a 3D microfluidic chip and self-developed software system to realize real-time monitoring. The system can ensure the steady transmission of droplets in long tubing without an external power source and generate stable droplets of suitable size for dPCR by two needles and a narrowed Teflon tube. The stable thermal cycle required by dPCR can be achieved by using only one constant temperature heater. In addition, our system has realized the real-time detection of droplet fluorescence in each thermal cycle, which makes up for the drawbacks of the end-point detection method used in traditional continuous-flow dPCR. This continuous-flow digital PCR by the compressed air-driven method can meet the requirements of droplet thermal cycle and diagnosis in a clinical-level serum sample. Comparing the detection results of clinical samples (hepatitis B virus serum) with commercial instruments (CFX Connect; Bio Rad, Hercules, CA, USA), the linear correlation reached 0.9995. Because the system greatly simplified the traditional dPCR process, this system is stable and user-friendly.

This paper presents a digital PCR system based on a novel thermal cycled chip, which wraps microchannels on a trapezoidal structure made of polydimethylsiloxane (PDMS) in a multi-helix manner for the first time. It is found that compared to the single helix chip commonly used in previous reports, this kind of novel multi-helix chip can make the surface temperature in the renaturation zone more uniform, and even in the case of rapid fluid flow, it can improve the efficiency of the polymerase chain reaction. What's more, the winding method of multi helix (such as double helix, six helix and eight helix) can obtain better temperature uniformity than the winding of odd helix (such as single helix and three helix). As a proof of concept, the temperature-optimized double-helical chip structure is applied to continuous-flow digital PCR and there is no need to add any surfactant to both the oil phase and reagent. In addition, we successfully analyzed the fluorescence signal of continuous-flow digital PCR by using CMOS camera. Finally, this method is applied for the absolute quantification of the clinical serum sample infected by HBV. The accuracy of the test results has been confirmed by commercial instruments.

Existing digital polymerase chain reaction (PCR) devices consist of multiple independent devices, such as a droplet generator, a PCR thermocycler, and a droplet reader, which have the disadvantages of low integration, complex equipment structure, and high operation difficulty. This paper proposes a fully automatic integrated digital PCR device based on continuous-flow digital PCR theory. By simply adding the sample to the entrance of the integrated instrument, a series of procedures required for digital PCR detection can be fully automated, including sample injection, droplet generation, PCR thermal cycling, fluorescence acquisition, and signal analysis. In contrast to traditional techniques, sample testing requires only one integrated device rather than three separate instruments. For full automation, we design complete control and data processing software, which can complete a test by one-step operation. Therefore, the disadvantages of traditional instruments, such as multi-step operation, and hence, potential environmental pollution, are avoided. Moreover, the system can be powered by solar cells and does not require an external power supply. As a proof of concept, the proposed device is used for absolute quantitative detection of the hepatitis B virus in serum samples. The capacity of the system is validated by absolute quantification of three orders of magnitude from 10 3 to 10 5 IU/mL. The results have a good linear correlation (0.9986) with those of the traditional quantitative (qPCR), thus confirming the reliability of the instrument. In summary, we believe that our work can promote the development of integrated digital PCR systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Temperature control is the most important and fundamental part of a polymerase chain reaction (PCR). To date, there have been several methods to realize the periodic heating and cooling of the thermal-cycler system for continuous-flow PCR reactions, and three of them were widely used: the thermo-cycled thermoelectric cooler (TEC), the heating block, and the thermostatic heater. In the present study, a new approach called open-loop controlled single thermostatic TEC was introduced to control the thermal cycle during the amplification process. Differing from the former three methods, the size of this microdevice is much smaller, especially when compared to the microdevice used in the heating block method. Furthermore, the rising and cooling speed of this method is much rapider than that in a traditional TEC cycler, and is nearly 20-30% faster than a single thermostatic heater. Thus, a portable PCR system was made without any external heat source, and only a Teflon tube-wrapped TEC chip was used to achieve the continuous-flow PCR reactions. This provides an efficient way to reduce the size of the system and simplify it. In addition, through further experiments, the microdevice is not only found to be capable of amplification of a PCR product from Human papillomavirus type 49 (Genbank ref: X74480.1) and Rubella virus (RUBV), but also enables clinical diagnostics, such as a test for hepatitis B virus.

A self-contained polymerase chain reaction (PCR) platform with miniaturized power-system is introduced. It is powered by portable lithium batteries and integrated continuous-flow PCR amplification platform. Generally speaking, traditional commercial thermal cyclers rely on external electric supply and thus they are too big in instrument size. This prevents real-timely and field testing during PCR diagnosis. The authors are introducing a continuous-flow 3D spiral microreactor for DNA amplifications and high-resolution multiplexed targets' detection by utilizing the polyvinyl chloride (PVC) tubing-polymer to fabricate the microreactor for the first time. The whole setup (that can all be placed in one hand) includes (a) the thermo-cycled control (5.5 cm width, 10 cm length and 11 cm height), (b) the passive continuous-flow control, and (c) the trapezoidal PCR microreactor. The PCR platform can work for 4.5 h continuously. With minimal accessories and operations, the total cost of the self-contained PCR machinery is <20 $, much lower than the mainstream of commercial PCR machinery. By waiving external electric supply, this miniaturized PCR platform is applied to amplify the typical DNA fragments of plasma isolated hepatitis B virus (HBV), influenza virus (H7N9avian influenza) bacterium (Escherichia coli) plasmid and multiplexed targets. The efficiency of the method is 70% of that of commercial thermal cycler (CFX Connect, Bio Rad). The DNA of H7N9avian influenza can be detected in concentrations as low as 10 3 copies per μL. Graphical abstract By utilizing the polyvinyl chloride (PVC) tubing-polymer to fabricate the microchip for the first time, this paper introduces a 3D spiral microreactor with a miniaturized power-system supplied by portable AA-batteries, applied in DNA amplifications and high-resolution multiplexed targets' detection. In this microdevice, we made the machinery portable by waiving the external plugs, which solved the problem of traditional commercial thermal cyclers about large volume and expensive price.

We introduce a new strategy for fabricating a seamless three-dimensional (3D) helical microreactor utilizing a silicone tube and a paraffin mold. With this method, various shapes and sizes of 3D helical microreactors were fabricated, and a complicated and laborious photolithographic process, or 3D printing, was eliminated. With dramatically enhanced portability at a significantly reduced fabrication cost, such a device can be considered to be the simplest microreactor, developed to date, for performing the flow-through polymerase chain reaction (PCR).

Consistent temperature control in an on-chip flow-through polymerase chain reaction (PCR) employing two or more heaters is one of the main obstacles for device miniaturization and integration when realizing micro total analysis systems (μTAS), and also leads to operational complexity. In this study, we propose a qiandu (right triangular prism)-shaped polydimethylsiloxane (PDMS) microdevice with serpentine microchannels fabricated on its slanted plane, and apply the device for an on-chip flow-through PCR employing a single heater. The inclined nature of the qiandu-shaped microdevice enables the formation of a surface temperature gradient along the slanted plane of the microdevice in a height-dependent manner by the use of a single heater, and enables liquid to traverse over wide ranges of temperatures, including the three temperature zones--denaturation, annealing, and extension temperatures--required in a typical PCR. The feasibility of the qiandu-shaped PDMS microdevice as a versatile platform for performing a flow-through PCR was examined by employing multiple templates and varying the inclination angle of the device. In addition, the potential of performing a multiplex PCR using a single qiandu-shaped PDMS microdevice was explored. A 409 bp long gene fragment effective as a marker for diagnosing lung cancer and a 230 bp long gene fragment from a plasmid vector were simultaneously amplified in less than 25 min on a single microdevice, paving the way for a microscale, multiplex PCR on a single device employing a single heater.

On-chip continuous-flow polymerase chain reactions (PCRs) generally require peripheral apparatus such as a pump for injecting a sample liquid into the fluidic channel. This makes the overall instrumentation bulky, limiting integration. In this study, we propose a new scheme for injecting a sample employing a hand-held syringe as a portable plastic pump, and apply it to an on-chip continuous-flow PCR. In the proposed injection scheme, sample actuation was realized inside a highly gas-permeable and blunt-ended fluidic conduit connected to a hand-held plastic syringe filled with compressed air. In this system, the degree of air diffusion via the walls of the gas-permeable conduit becomes greater in the anterior (closer to the outlet) end of the sample plug than the posterior (closer to the inlet) end, because a relatively larger quantity of air is retained inside the syringe at the posterior end of the sample plug. This creates a pressure gradient at the inlet and outlet of the fluidic conduit and propels the sample forward toward the outlet. Preliminary experiments were performed for the quantitative analyses and evaluation of the proposed sample injection scheme using gas-permeable silicone tubes. As practical applications, a 230 bp gene fragment from a plasmid vector and the first 282 bp of the interferon-beta (IFN-β) promoter from a human genomic DNA were successfully amplified on a microdevice coupled with a hand-held syringe as a portable sample actuation device, greatly enhancing device portability for on-site analyses.

Bubble formation inside a microscale channel is a significant problem in general microfluidic experiments. The problem becomes especially crucial when performing a polymerase chain reaction (PCR) on a chip which is subject to repetitive temperature changes. In this paper, we propose a bubble-free sample injection scheme applicable for continuous-flow PCR inside a glass/PDMS hybrid microfluidic chip, and attempt to provide a theoretical basis concerning bubble formation and elimination. Highly viscous paraffin oil plugs are employed in both the anterior and posterior ends of a sample plug, completely encapsulating the sample and eliminating possible nucleation sites for bubbles. In this way, internal channel pressure is increased, and vaporization of the sample is prevented, suppressing bubble formation. Use of an oil plug in the posterior end of the sample plug aids in maintaining a stable flow of a sample at a constant rate inside a heated microchannel throughout the entire reaction, as compared to using an air plug. By adopting the proposed sample injection scheme, we demonstrate various practical applications. On-chip continuous-flow PCR is performed employing genomic DNA extracted from a clinical single hair root sample, and its D1S80 locus is successfully amplified. Also, chip reusability is assessed using a plasmid vector. A single chip is used up to 10 times repeatedly without being destroyed, maintaining almost equal intensities of the resulting amplicons after each run, ensuring the reliability and reproducibility of the proposed sample injection scheme. In addition, the use of a commercially-available and highly cost-effective hot plate as a potential candidate for the heating source is investigated.

Multi-step temperature control in a polymerase chain reaction (PCR) is a limiting factor in device miniaturization and portability. In this study, we propose the fabrication of a three-dimensional (3D) microdevice employing a single heater to minimize temperature control required for an on-chip continuous-flow PCR as well as the overall footprint by stacking the device in multi-layers. Two poly(dimethylsiloxane) (PDMS) layers with differing thicknesses are vertically stacked with their microchannel-engraved sides facing down. Through-holes are made in the thicker PDMS layer, which is sandwiched between a glass substrate at the bottom and the thinner PDMS layer at the top. In this way, a fluidic conduit is realized in a 3D configuration. The assembled 3D microdevice is then placed onto a heater glass-side down. The interface of the two PDMS layers displays a relatively lower temperature than that of the PDMS and glass layers due to the low thermal conductivity of the PDMS and its physical distance from the heater. The denaturation temperature can be controlled by adjusting the temperature of the heater, while the annealing/extension temperature can be controlled automatically by molding the thicker bottom PDMS layer into the appropriate thickness calculated using a numerical derivation proposed in this study. In this way, a cumbersome temperature measurement step is eliminated. DNA amplification was successfully carried out using the proposed 3D fluidic microdevice, and the intensity of the resulting amplicon was comparable to that obtained using a thermal cycler. This novel concept of adopting a single heating source greatly simplifies the temperature control issue present in an on-chip continuous-flow PCR. It also allows the use of a commercialized hot plate as a potential heat source, paving the way for device miniaturization and portability in a highly cost-effective manner. In this study, a simple and facile technique to make arrays of through-holes for the fluidic interconnection inside a 3D channel configuration is also addressed.

Purpose: This paper aims to introduce a custom-designed integrated nucleic acid detection polymerase chain reaction (PCR) instrument for clinical detection applications. Design/methodology/approach: The PCR instrument can make rapid, sensitive, low-cost and quantitative molecular diagnosis compared with the current routine test flow from the pipette, series reagent to RT-PCR by manual manipulation. By integrating the multichannel automatic pipetting module, heat amplification module and real-time fluorescence detection module for the first time, the custom-designed integrated nucleic acid detection PCR instrument can achieve sample collection, subpackage, mixing, extracting, measuring and result presentation. Findings: The multichannel automatic pipetting module was assembled with an accuracy of 0.4% (2 microliters) for accuracy measurement. Besides, the accuracy and sensitivity of nucleic acid using integrated low-cost nucleic acid detection PCR instruments were checked with COV-2019 virus (staining method) and African swine fever virus (probe method) under different concentrations. Practical implications: Because of its high cost, complex system and bulky laboratory settings, including sample subpackage, mixing, extracting, measuring and finally result in presentation, the current nucleic acid detection system is not suitable for field operation and disease diagnosis in remote areas. The group independently designed and assembled an integrated low-cost multichannel nucleic acid detection PCR instrument, including a multichannel automatic pipetting module, a heat amplification module and a real-time fluorescence detection module. Originality/value: The above equipment showed better reliability compared with commercial qPCR. These results can lay the foundation for functional, fast and low-cost PCR equipment for trace measurements. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic poses a threat to global health. Due to its high sensitivity, specificity, and stability, real-time fluorescence quantitative (real-time PCR) detection has become the most extensively used approach for diagnosing SARS-CoV-2 pneumonia. According to a report from the World Health Organization, emerging and underdeveloped nations lack nucleic acid detection kits and polymerase chain reaction (PCR) instruments for molecular biological detection. In addition, sending samples to a laboratory for testing may result in considerable delays between sampling and diagnosis, which is not favorable to the timely prevention and control of new crown outbreaks. Concurrently, there is an urgent demand for accurate PCR devices that do not require a laboratory setting, are more portable, and are capable of completing testing on-site. Hence, we report on HDLRT-qPCR, a new, low-cost, multiplexed real-time fluorescence detection apparatus that we have developed for on-site testing investigations of diverse diseases in developing nations. This apparatus can complete on-site testing rapidly and sensitively. The entire cost of this instrument does not exceed USD 760. In order to demonstrate the applicability of our PCR instrument, we conducted testing that revealed that we achieved gradient amplification and melting curves comparable to those of commercially available equipment. Good consistency characterized the testing outcomes. The successful detection of target genes demonstrates the reliability of our inexpensive PCR diagnostic technique. With this apparatus, there is no need to transport samples to a central laboratory; instead, we conduct testing at the sampling site. This saves time on transportation, substantially accelerates overall testing speed, and provides results within 40 min. [ABSTRACT FROM AUTHOR]

Programmed mini-pumps play a significant role in various fields, such as chemistry, biology, and medicine, to transport a measured volume of liquid, especially in the current detection of COVID-19 with PCR. In view of the cost of the current automatic pipetting pump being higher, which is difficult to use in a regular lab, this paper designed and assembled a three-dimensional programmed mini-pump with the common parts and components, such as PLC controller, motor, microinjector, etc. With the weighting calibration before and after pipetting operation, the error of the pipette in 10 μ L (0.2%), 2 μ L (1.8%), and 1 μ L (5.6%) can be obtained. Besides, the contrast test between three-dimensional programmed mini-pump and manual pipette was conducted with the ORF1ab and pGEM-3Zf (+) genes in qPCR. The results proved that the custom-made three-dimensional programmed mini-pump has a stronger reproducibility compared with manual pipette (ORF1ab: 24.06 ± 0.33 vs. 23.50 ± 0.58, p = 0.1014; pGEM-3Zf (+): 11.83.06 ± 0.24 vs. 11.50 ± 0.34, p = 0.8779). These results can lay the foundation for the functional, fast, and low-cost programmed mini-pump in PCR or other applications for trace measurements. [ABSTRACT FROM AUTHOR]

The polymerase chain reaction (PCR) has unique advantages of sensitivity, specificity and rapidity in pathogen detection, which makes it at the forefront of academia and application in molecular biology diagnosis. In this study, we proposed a hand-held real-time fluorescence qPCR system, which can be used for the quantitative analysis of nucleic acid molecules. For the first time, we use a PVC microreactor which improved the transmittance of the microreactor and made it easy to collect the fluorescence signal. In order to make it portable, the system adopted a passive syringe for sample injection and integrated temperature control and detection with a lithium battery for power supply. What's more, the fluorescence signal was captured by using a smartphone through an external automatic robotic arm. This real-time qPCR system can detect genomic DNA of the H7N9 avian influenza over four orders of magnitude of concentration from 107 to 104 copies per μL. In addition, it was verified that the fluorescence images obtained by this system were clearer than those obtained by a traditional system (using a PTFE spatial PCR microreactor) with two typical dyes and a probe tested—EvaGreen, SYBR Green and FAM. [ABSTRACT FROM AUTHOR]

An open system with a thermal gradient is described for the optimization of polymerase chain reactions (PCR). Two thermal electric coolers were used as the heat source. The gradient is measured through encapsulated water-based beads of a temperature-dependent dye inside mineral oil, thereby forming virtual reaction chambers. Nine droplets (with typical volume of 0.7 μL) were used. Using the intrinsic fluorescence of a temperature-sensitive inert dye (sulforhodamine B), the process involves measurement of the fluorescence intensity at a known, uniform temperature together with the instrument-specific calibration constant to calculate an unknown, possibly non-uniform temperature. The results show that a nearly linear thermal gradient is obtained. This gradient function is a useful feature that can be used for optimization of a commonly used enzyme-activated reaction, viz. PCR. The emission spectra of fluorescent droplets during two-step PCR were monitored and the changes in fluorescence between 50 °C and 100 °C quantified. As the gradient feature allows for testing a range of annealing temperatures simultaneously, the optimal annealing temperature can be easily determined in a single experiment. [ABSTRACT FROM AUTHOR]

We report on a bent microdevice made from elastomeric polydimethylsiloxane (PDMS) on a polycarbonate (PC) solid support. Its bent shape is well sustained, and this allows an on-chip flow-through polymerase chain reaction (PCR) to be performed employing a single heater. The PC support was bent to a predetermined angle by heating the substrate close to the glass transition temperature of PC, and the PDMS microdevice was physically adapted to the curvature of the bent PC. The relatively short plane of the bent PC substrate was then placed on top of a heater, leaving the relatively long plane floating in the air, on the entire surface of which a temperature gradient was established. The plane in contact with the heater represents the zone for denaturation, and the slanted plane floating in the air acts as the annealing/extension zone. Two targets with amplicon sizes of 230 and 282 bp were successfully amplified utilizing microdevices with 4° and 17° inclination angles, respectively, by employing a single heater in both cases and within 30 min. The system provides an effective alternative to conventional 3-temperature control flow-through PCR devices by minimizing the accessories and hence facilitating system miniaturization. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this study, we fabricate a hybrid planar microdevice to perform an on-chip flow-through polymerase chain reaction (PCR) constructed by assembling glass and poly(dimethylsiloxane) (PDMS) on which a serpentine microchannel is engraved. The proposed system employs a metal alloy slab, called Invar, which is basically a nickel iron alloy, sandwiched between the microdevice and a heater. Owing to the high thermal conductivity (10WK−1 m−1) but notably low thermal expansion coefficient (1.6×10−6 K−1) of Invar, a stable temperature gradient was established on its surface. The Invar was placed on the heater in such a way that they made partial contact, with the rest of the Invar exposed to the air. A uniformly distributed temperature gradient, which ranged in temperatures from 57°C to 95°C, was first established on the Invar sheet, and a planar microdevice was directly placed atop the Invar sheet. The proposed system was successfully applied to amplify three targets: a 230bp gene fragment from a plasmid vector, the first 282bp of the interferon-beta (IFN-β) promoter from human genomic DNA, and a 409bp long gene fragment in thyroid transcription factor-1 (TTF-1), which is used effectively as a marker for diagnosing lung and thyroid carcinomas, from human genomic DNA. All of the targets were amplified within less than 30min. One microdevice was utilized repeatedly for multiple target amplifications by fine tuning the relative position of the Invar sheet on the heater. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the fabrication of a two-layer microdevice for conducting on-chip parallel flow-through polymerase chain reactions (PCRs) equipped with a single heater and disposable plastic syringes for semi-automated sample delivery for the construction of a portable PCR microdevice. Identical shapes of disconnected spiral-like microchannels were engraved on two poly(dimethylsiloxane) (PDMS) substrates having varying thicknesses, and by rotating either one of the substrates 180°, they were aligned in such a way that one continuous sample flow was realized in a 3D configuration within a two-layer microdevice. Typical in vitro enzymatic amplifications were performed simultaneously in parallel on the microdevice by employing a single heater. Also, sample actuation module was miniaturized and its operation was semi-automated by employing portable plastic syringes as pumps. This system dispenses with the use of a bulky external apparatus such as a syringe pump, and also greatly simplifies the temperature control by utilizing a single heater, and therefore, downsizing the overall footprint of the device. Samples were injected into two inlets simultaneously and were successfully delivered through the entire length of the microchannels of over 2m, mediated by portable plastic syringes. To investigate the feasibility of employing a single heater as well as to assess the reliability of the sample injection performance initiated by the plastic syringes, on-chip flow-through PCRs were performed using plasmid DNA as templates inside 2m-long spiral microchannels constructed in a two-layer arrangement, as a proof-of-concept experiment. Target amplicons were successfully amplified simultaneously in parallel reactions inside the proposed microdevice in approximately 27min with high reproducibility, confirming stable sample injection performance and reliable temperature control inside the microdevice. The proposed schemes could pave the way for device miniaturization, process simplification, and reaction parallelization, realizing a portable microfluidic device applicable for on-site and direct field uses. [Copyright &y& Elsevier]

In recent years, the development of polymerase chain reaction (PCR) technology has focused on digital PCR, which depends on the microfluidics. Based on continuous-flow microfluidic technology, this paper designed a miniaturized digital PCR amplification system, and greatly reduced the area required for microdroplet generation and reaction. The core rod. made of polydimethylsiloxane (PDMS), was combined with the Teflon tube to form 3D microfluidics, which requires only one heating source to form the temperature difference required for gene amplification. Only two 34 g needles can form and transmit micro-droplets in a 4-fold tapered Teflon tube, which is the simplest method to generate digital PCR droplets as far as we know, which allows the microdroplet generation device to be free from dependence on expensive chips. A complementary metal oxide semiconductor (CMOS) camera was used as a detection tool to obtain fluorescence video for the entire loop area or a specified loop area. In addition, we developed a homebrew for automatic image acquisition and processing to realize the function of digital PCR. This technique realizes the analysis of clinical serum samples of hepatitis B virus (HBV) and obtained the same results as real-time quantitative PCR. This system has greatly reduced the size and cost of the entire system, while maintaining a stable response. [ABSTRACT FROM AUTHOR]

The traditional qPCR instrument is bulky, expensive, and inconvenient to carry, so we report a portable rotary real-time fluorescent PCR (polymerase chain reaction) that completes the PCR amplification of DNA in the field, and the reaction can be observed in real-time. Through the analysis of a target gene, namely pGEM-3Zf (+), the gradient amplification and melting curves are compared to commercial devices. The results confirm the stability of our device. This is the first use of a mechanical rotary structure to achieve gradient amplification curves and melting curves comparable to commercial instruments. The average power consumption of our system is about 7.6 W, which is the lowest energy consumption for real-time fluorescence quantification in shunting PCR and enables the use of our device in the field thanks to its self-contained power supply based on a lithium battery. In addition, all of the equipment costs only about 710 dollars, which is far lower than the cost of a commercial PCR instrument because the control system through mechanical displacement replaces the traditional TEC (thermoelectric cooler) temperature control. Moreover, the equipment has a low technical barrier, which can suit the needs of non-professional settings, with strong repeatability. [ABSTRACT FROM AUTHOR]

Real-time polymerase chain reaction (PCR) is the standard for nucleic acid detection and plays an important role in many fields. A new chip design is proposed in this study to avoid the use of expensive instruments for hydrophobic treatment of the surface, and a new injection method solves the issue of bubbles formed during the temperature cycle. We built a battery-powered real-time PCR device to follow polymerase chain reaction using fluorescence detection and developed an independently designed electromechanical control system and a fluorescence analysis software to control the temperature cycle, the photoelectric detection coupling, and the automatic analysis of the experimental data. The microchips and the temperature cycling system cost USD 100. All the elements of the device are available through open access, and there are no technical barriers. The simple structure and manipulation allows beginners to build instruments and perform PCR tests after only a short tutorial. The device is used for analysis of the amplification curve and the melting curve of multiple target genes to demonstrate that our instrument has the same accuracy and stability as a commercial instrument. [ABSTRACT FROM AUTHOR]

A self-activated micropump which is capable of stable velocity transport for a liquid to flow a given distance inside a 3D microchannel has been a dream of microfluidic scientists for a long time. A new self-activated pumping mechanism has been proposed in this paper. It is different from the authors' previous research which relied on the fluid resistance of a quartz capillary tube or end-blocked gas-permeable silicone or a polydimethylsiloxane (PDMS) wall to automate the flow. In this research, an end-open stretched Teflon tube was utilized for passive transport for the first time. A new fluid transmission mode was adopted with the assistance of a cheaper easily accessible oil mixture to achieve stable continuous flow. Finally, this novel micropump has been applied to real-time continuous-flow polymerase chain reactions (PCRs), with an amplification efficiency similar to that of a commercial PCR cycler instrument. [ABSTRACT FROM AUTHOR]