IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 14, Issue 3 Ser. III (May. – June. 2019), PP 45-53 www.iosrjournals.org DOI: 10.9790/1676-1403034553 www.iosrjournals.org 45 | Page Design and Development of Embedded System Based PCR Thermal Cycler V.Sailaja 1 , Ramesh Datla 2 , K.Nagabhushan Raju 3 , M. Lakshmi Prasad 4 1, 3 Department of Instrumentation, Sri Krishnadevaraya University, Anantapur, INDIA 2, 4 ELICO Limited, Hyderabad, Telangana, INDIA Corresponding Author: V.Sailaja Abstract: In this paper we present the design and development of embedded system based Polymerase Chain Reaction (PCR) Thermal Cycler. The development steps of PCR thermal cycler are explained. Important design features of thermal cycler and their implementation are discussed. The results of the developed PCR thermal cycler are compared with those of benchmark instruments. Keywords: PCR, Peltier, Hardware, Software, Thermal Cycling. -------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 01-07-2019 Date of acceptance: 16-07-2019 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Polymerase Chain Reaction (PCR), is a method of in vitro enzymatic synthesis and amplification of specific DNA fragments. PCR was invented by Dr. Kary Mullis in the 1980s. Mullis was awarded Nobel Prize in Chemistry in 1993 for this invention [1]. With the development and breakthrough of science and technology, PCR technology has been widely used in many fields, such as microbial detection, veterinary medicine, aquaculture and so on. PCR has various applications, including molecular diagnostics of human and animal diseases, forensics [5], food technology [6] and environmental studies [7, 8]. This technique has strong sensitivity, accuracy and specificity, And it can be detected quickly, so its application field is extending continuously [2, 3]. PCR technology is based on the known DNA sequence, to be amplified with the synthetic DNA two chain end complementary two oligonucleotide primers, in vitro to be detected DNA sequences (template) were amplified in enzymatic action. During amplification, the sample is cycled between denaturation, annealing and extension temperature. The typical ranges of denaturation and annealing are, respectively, 90- 95°C and 50-65°C. The extension happens around 72°C. The whole technical process of PCR by several cycles, one cycle consists of 3 steps: The first step is the continuous DNA template degeneration under high temperature conditions, namely the template DNA at 93~94 ℃ under the condition of denaturation chain; the second step is that annealing synthetic oligonucleotide primer and template DNA chain. By the end of the cooling to 55 ℃ annealing; the third step is to extend, which exist at the same time in 4 kinds of d NTP substrate, with the help of Taq DNA polymerase, primers chain along the 5'-3' direction and new chain of complementary template. After this cycle, a new chain is synthesized that can be continued as a DNA template and thus recycled. During the cycle, the amount of amplified products increased exponentially, and the single copy gene is 25~40 times [4], and DNA could amplify l00 million times. The steps of the PCR reaction are simple, but the specific operations are complex, such as the determination of the annealing temperature, the length of the extension and the number of cycles. Experimental steps of the PCR procedure are sample preparation, DNA amplification and product detection. The PCR protocol is as shown in Table 1. A PCR thermal cycler is a device temperature-monitoring and controlling of the temperature of an aluminum block in order to deliver the temperature required by each chain reaction step of PCR protocol. Thermal block in the Fig.1 is to conduct three steps of PCR, denaturation, annealing and extension. DNA reaction mixture contains the target DNA, primers, nucleotides and DNA polymerase. Heated lid at the top of the mixture is to suppress condensation in the tube. Temperature of the heated lid remains the same and is kept above the denaturation temperature. PCR thermal cycler is also called qualitative PCR. Its components are of macroscopic size. Normally, it uses Peltier cell thermal cycling. Other parts include power system and temperature control system. Micro litres of DNA mixture of is needed. Several samples can be processed or analyzed simultaneously. DNA amplification up to millions is possible in hours time scale.