Electrical detection of dsDNA and polymerase chain reaction amplification

Abstract

Food-borne pathogens and food safety-related outbreaks have come to the forefront over recent years. Estimates on the annual cost of sicknesses, hospitalizations, and deaths run into the billions of dollars. There is a large body of research on detection of food-borne pathogens; however, the widely accepted current systems are limited by costly reagents, lengthy time to completion, and expensive equipment. Our aim is to develop a label-free method for determining a change in DNA concentration after a PCR assay. We first used impedance spectroscopy to characterize the change in concentration of purified DNA in deionized water within a microfluidic biochip. To adequately measure the change in DNA concentration in PCR solution, it was necessary to go through a purification and precipitation step to minimize the effects of primers, PCR reagents, and excess salts. It was then shown that the purification and precipitation of the fully amplified PCR reaction showed results similar to the control tests performed with DNA in deionized water. We believe that this work has brought label free electrical biosensors for PCR amplification one step closer to reality.

Ultralocalized thermal reactions in subnanoliter droplets-in-air

“…Earlier studies have indicated this results in joule heating due to the mobile ions responding to the electric field within the double layer at regions of high electric field above the device. Previous studies have also shown that DNA-in-water solutions have a strong relaxation point in the low MHz regime (32,33). This is typically considered to be due to counter ion movement around the transverse axis of the DNA molecule (34)(35)(36).…”

Temperature Sensors for Biochips Based on Resistance Temperature Detectors Using Copper Pattern on Printed Circuit Board

“…Temperature sensors such as thermocouple sensors, thermistors, and resistance temperature detectors (RTD) can be installed on the PCB substrate, on the opposite side of the platform where the DNA is amplified. (4)(5)(6)(7)(8) Our group previously demonstrated successful DNA amplification using a PCB-based PCR chip with a thermistor having 1% resistance tolerance embedded into the PCB substrate. (9) In the previous work, the PCR results from several PCR chips with thermistors having different error rates were statistically analyzed using the band volume of the gel image after amplification.…”

Resistance Temperature Detector Sensor with a Copper Pattern on the Printed Circuit Board

“…Temperature sensors such as thermocouple sensors, thermistors, and resistance temperature detectors (RTD) are installed in the biochip, on the surface where the DNA is amplified, for this purpose [4][5][6][7][8].…”