Review of ultrasensitive readout for micro-/nanofluidic devices by thermal lens microscopy

Thermal lens microscopy (TLM) utilizes the effects, such as changes in the refractive index, caused by heat generated in the sample for the detection of nonfluorescent analytes with at least a hundred-fold enhancement in sensitivity compared with optical absorbance spectrometry. Micro-/nanofluidic devices can provide specificity and sample manipulation capabilities. The integration of these two technologies exposes the potential to attain the holy grail of continuous, real-time, label-free, specific, and ultrasensitive detection, which find applications in environmental monitoring, quality control of chemical manufacturing, single-cell analysis, and biomedicines. Here, we summarize the recent advances in the instrument development and innovative applications, and suggest future directions of research of TLM.