BackgroundIn general, the image analysis of nucleic acid for detecting DNA is dependent on the gel documentation system. These experiments may deal with harmful staining agents and are time consuming. To address these issues, real-time polymerase chain reaction (PCR) devices have been developed. The advantages of real-time PCR are its capabilities for real-time diagnosis, improved sensitivity, and digitization of measurement results. However, real-time PCR equipment is still too bulky and expensive for use in small hospitals and laboratories.MethodsThis paper describes an evaluation-independent real-time PCR system that differs from conventional systems in that it uses a side-illumination optical detection system and a temperature adjustment coefficient for DNA detection. The overall configuration of the evaluation-independent system includes the PCR chip and system hardware and software. The use of the side-illumination method for detection enables the system size to be reduced compared to systems using a typical illumination method. Furthermore, the results of a PCR test are strongly affected by the reaction temperature. Thus, extremely precise control of the temperature of the reaction is needed to obtain accurate results and good reliability. We derived a temperature compensation coefficient that allows us to compensate for the differences between the measured temperature of the negative temperature coefficient (NTC) thermistor sensor and the real temperature of the thermocouple.ResultsApplying the temperature compensation coefficient parameter using the NTC thermistor and using the side-illumination method resulted in an increase in the initial sensor value. The occurrence of the DNA section amplification decreased to 22 cycles from 24 cycles.ConclusionsThe proposed system showed comparable performance to that of an existing real-time PCR, even with the use of simpler and smaller optical devices.

The polymerase chain reaction is an important technique in biological research because it tests for diseases with a small amount of DNA. However, this process is time consuming and can lead to sample contamination. Recently, real-time PCR techniques have emerged which make it possible to monitor the amplification process for each cycle in real time. Existing camera-based systems that measure fluorescence after DNA amplification simultaneously process fluorescence excitation and emission for dozens of tubes. Therefore, there is a limit to the size, cost, and assembly of the optical element. In recent years, imaging devices for high-performance, open platforms have benefitted from significant innovations. In this paper, we propose a fluorescence detector for real-time PCR devices using an open platform camera. This system can reduce the cost, and can be miniaturized. To simplify the optical system, four low-cost, compact cameras were used. In addition, the field of view of the entire tube was minimized by dividing it into quadrants. An effective image processing method was used to compensate for the reduction in the signal-to-noise ratio. Using a reference fluorescence material, it was confirmed that the proposed system enables stable fluorescence detection according to the amount of DNA.

No abstract

In general, DNA detection involves the following four steps: DNA extraction, DNA amplification, electrophoresis, and gel image analysis. Each step requires expensive equipment. Generally, a gel documentation system is widely used as a DNA detector. For the analysis of gel images, the most expensive imaging systems are used. Therefore, various studies are under way to create a gel documentation system of small size and low cost. In recent years, the rapidly developing open platform has been applied to various embedded systems. The open platform provides connectivity from a local area network to a global area network, making it easy to build various systems embedded into an Internet-of-Things (IoT) system. In other words, using the open platform makes it easier to develop an embedded system that can be accessed anytime and anywhere. In this paper, we propose a gel documentation system and compare its performance with that of the existing system, because the high-quality smartphone camera is being continuously developed for the open platform. Experimental results show that the proposed system has performance characteristics similar to those of the existing system while showing superiority in terms of price, size, and user convenience.

The general polymerase chain reaction (PCR) amplifies DNA and analyzes the amplification results of the quantified DNA. Recently, real-time PCR has been developed to detect DNA amplification in various ways. The conventional camera-based system is too expensive and difficult to reduce device size. In this paper, we propose a low-cost, compact fluorescence detection system for real-time PCR systems using an open platform camera. To simplify the optics, four low-cost small cameras were fixedly placed, and the entire tube was divided into four quadrants to minimize the field of view. In addition, an effective image processing method was used to compensate. The proposed system measured the fluorescence detection performance on the basis of the amount of DNA using various fluorescent substances.