Temperature gradient based wire-guided rapid pcr system

Abstract

Polymerase chain reaction (PCR) is an integral part of modern day biological research and medical care. PCR has applications in areas such as pathogen detection, medical diagnosis, forensics and genetic research. This process of amplifying DNA relies on the repeated heating and cooling of an enzyme-containing solution. Typical PCR machines, especially thermocyclers, are costly and take 1-3 hours to complete 25-50 cycles of DNA amplification. This lengthy duration is due to the slow conductive heating mechanism employed by the thermocycler. New developments have been able to greatly reduce the amplification time to under 10 minutes by working with a smaller sample size and employing more effective heat transfer methods. One interesting and effective method involves a series of oil baths heated to different temperatures. A tiny droplet of fluid is moved between the baths, allowing for quick convective heat transfer. However, this process requires multiple heaters and an advanced control strategy to maintain the three temperatures required for PCR and to move the droplet between them. This paper describes a new method under development, based off of the one just described, that will simplify the system by utilizing a single oil bath with a heat gradient ranging from [Greater Than]95 degree Celcius to [Less Than]60 degree Celcius. Within this gradient are all of the required temperatures needed for PCR, and by guiding the droplet back and forth through the oil we can quickly change the temperature of the sample. A single temperature transducer alongside the droplet will provide constant sample-temperature feedback to the controller, thus simplifying the current control strategy. This device has the potential to be smaller, cheaper and faster than the current wire-guided droplet PCR device, which has accomplished 30 cycles in 7 minutes.