Low-power microwave-mediated heating for microchip-based PCR

Abstract

Microwave energy has been used to rapidly heat food and drinks for decades, in addition to assisting other chemical reactions. However, only recently has microwave energy been applied in microfluidic systems to heat solution in reaction chambers, in particular, the polymerase chain reaction (PCR). One of the difficulties in developing microwave-mediated heating on a microchip is the construction of the appropriate architecture for delivery of the energy to specific micro-areas on the microchip. This work employs commercially-available microwave components commonly used in the wireless communications industry to generate a microwave signal, and a microstrip transmission line to deliver the energy to a 1 μL reaction chamber fabricated in plastic microdevices. A model was developed to create transmission lines that would optimally transmit energy to the reaction chamber at a given frequency, minimizing energy usage while focusing microwave delivery to the target chamber. Two different temperature control methods were demonstrated, varying microwave power or frequency. This system was used to amplify a fragment of the lambda-phage genome, thereby demonstrating its potential for integration into a portable PCR system.

Novel Fabrication Process for Integration of Microwave Sensors in Microfluidic Channels

“…Microwave technology is a powerful tool for biomedical application that enables label-free sensing and broadband spectroscopy for cells, tissues, and proteins [10]. In recent years, a new subdomain called microwave-micofluidics has gained popularity, which integrates microwave circuits and microfluidic channels to provide a new superior tool for biomedical applications, including nanoliter bioliquid broadband spectroscopy [10,11], single cell broadband spectroscopy [12,13], liquid mixture sensing [14,15], flow cytometry [16], and microwave heating for continuous [17,18] and digital [19,20] microfluidic applications, such as microchip-based polymerase chain reaction (PCR) [21]. Polydimethylsiloxane (PDMS)-based microfluidic devices have broad applications in biological studies, because of its low cost, non-toxicity to cells, permeability to gases [22], and chemical compatibility with various of solvents solvents [23].…”

A Low-Cost and Fast Real-Time PCR System Based on Capillary Convection

“…To bring sensitive molecule diagnostics into a doctor's office, on-site environment, and rural clinics with poor medical resources (e.g., in point-of-care settings), temperature control for nucleic acid amplification should be simplified to reduce the amplification time as well as the device complexity. 2 More recently, isothermal nucleic acid amplification methods, such as loop-mediated isothermal amplification (LAMP), nucleic acid sequence-based amplification (NASBA), and rolling circle amplification (RCA), have been developed with simplified temperature settings. [3][4][5] The inconveniences with isothermal amplification include the large number of primers and their quantification method of the template.…”

Characterization and analysis of real-time capillary convective PCR toward commercialization

“…To reduce amplification time, small size PCR reactors as well as high energy power based heating strategies have been developed to speed up the ramping rate of thermal cycling. 7,8 However, detection sensitivity may be decreased by small size reactors with low quantity of templates. 9 Device complexity and cost will be increased with high energy power based heating because of high cost components and elaborate control strategy.…”