2.4. Operation
The chambers with the resistive heater on the backside, are intensively cleaned by rinsing with acetone, MilliQ DI water, ethanol, and isopropanol [45]. Each cleaning step was done 3 times and the chips are blow dried using N2 gas. After drying, the chambers are closed using Microseal “B” PCR plate sealing foil from Bio-Rad (Bio-Rad Inc., Hercules, CA, USA), which is cut in the proper size and manually attached on top of the substrate (see Figure 4e). The DNA, reactants and buffer solutions from the Illustra GenomiPhi V2 DNA amplification kit and an EvaGreen fluorescence dye are pipetted inside the chip using the inlet aperture, after which the inlet and outlet are closed using the same PCR foil. An input potential is applied on the resistive heater using a Keithley 2602 SYSTEM SourceMeter (Cleveland, OH, USA) until they acquire the desired temperature for the amplification. The temperature is real-time monitored by inserting a 162 series RS Technics thermocouple K (RS Components B.V., Haarlem, The Netherlands) in the temperature monitor chamber. The thermocouple is read out with a Tenma 72-7715 Thermometer (Premier Farnell Ltd., Leeds, UK). The source and the read-out of the thermocouple are operated using a custom-programmed LabVIEW program. The initial potential is based on the heater characterization measurements, but will be adjusted according to the feedback-loop of the thermocouple. Detection of the amplification is done ex-situ by using quartz cuvets and an Horiba Scientific FluoroMax+ spectrofluorometer (Horiba Scientific, Piscataway, NJ, USA).