Easley Christopher J, Legendre Lindsay A, Roper Michael G, Wavering Thomas A, Ferrance Jerome P, Landers James P
Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA.
Anal Chem. 2005 Feb 15;77(4):1038-45. doi: 10.1021/ac048693f.
Optical fiber extrinsic Fabry-Perot interferometry (EFPI) was investigated as a noncontact temperature sensor and utilized for regulating the temperature of small-volume solutions in microchips. Interference pattern analysis determined the optical path lengths (OPL) associated with reflections from various surfaces on or in the microchip, in particular, from gold sputtered on the bottom of a microchannel. Since OPL is directly proportional to refractive index, which is dependent on solution temperature, the EFPI sensor was capable of noncontact monitoring of solution temperature simply from alterations in the measured path length. Calibration of the sensor against a thermocouple was performed while heating the microchip in a noncontact manner with an IR lamp. The combination of EFPI temperature sensor, IR-mediated heating, and air cooling allowed a fully noncontact system for small-volume temperature control in microchip structures, and its utility was illustrated by optimal digestion of DNA by a temperature-dependent restriction endonuclease in 320 nL. The functionality and simplicity of the microchip EFPI temperature sensor was enhanced by replacing the prebonding sputtered gold with a tunable, chemically plated semireflective silver coating created in situ after chip fabrication. This provided an 8-fold improvement in the lowest detectable temperature change (deltaT = 0.1 degrees C), facilitated primarily by enhanced reflection from both the bottom and top surfaces of the microchannel. This approach for controlling micro- and nanoscale reactions--with heating, cooling, and temperature control being carried out in a completely noncontact fashion--provides an accurate and sensitive method for executing chemical and biochemical reactions in microchips.
光纤外腔法布里-珀罗干涉测量法（EFPI）作为一种非接触式温度传感器进行了研究，并用于调节微芯片中小体积溶液的温度。干涉图样分析确定了与微芯片上或内部各个表面（特别是微通道底部溅射的金）的反射相关的光程长度（OPL）。由于光程长度与折射率成正比，而折射率又取决于溶液温度，因此EFPI传感器能够仅通过测量路径长度的变化对溶液温度进行非接触监测。在用红外灯以非接触方式加热微芯片的同时，将传感器与热电偶进行了校准。EFPI温度传感器、红外介导加热和空气冷却的组合，使得在微芯片结构中实现了用于小体积温度控制的完全非接触系统，并且通过一种温度依赖性限制内切酶在320 nL溶液中对DNA进行最佳消化，展示了其效用。通过在芯片制造后原位创建的可调谐化学镀半反射银涂层替代预键合溅射金，增强了微芯片EFPI温度传感器的功能和简易性。这使得最低可检测温度变化提高了8倍（ΔT = 0. l℃），这主要得益于微通道底部和顶部表面反射的增强。这种以完全非接触方式进行加热、冷却和温度控制来控制微纳尺度反应的方法，为在微芯片中进行化学和生化反应提供了一种准确且灵敏的方法。
