Abstract
A dual-channel flow-through microcalorimeter device is presented along with a non-contact precision method of temperature calibration. A microfluidic channel with a volume of ≈550 pL in a spiral layout was fabricated from low-stress nitride suspended over a cavity in a silicon substrate. The thin-film heater and resistive temperature detector (RTD) on the channel were defined by a patterned Ti layer. The device exhibited a rapid thermal response with the following thermal characteristics: a time constant of ≈10.5 ms, a heat conductance of $\approx 152~\mu ~\text{W}\,\cdot ~{\mathrm {K}}^{-{1}} $ and a heat capacitance of $\approx 1.6~\mu \text{J}\,\cdot {\mathrm {K}}^{-{1}} $ on average based on the measurements of nine separate units fabricated on the same wafer. Further, the melting curve analysis (MCA) of a double-stranded DNA was proposed as a non-contact method of microcalorimeter RTD calibration. The method revealed that the measurement by the RTD underestimates the temperature of the channel interior by an amount of nearly 15%, at ≈ 9 mW. At this dissipated power level, the method also revealed a spatial nonuniformity of ≈ ± 0.8 °C across the microcalorimeter. [2020-0173]
Published Version
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