An ultrasensitive terahertz microfluidic chip based on Fano resonance of a few arrays of meta-atoms

We present a nonlinear optical crystal-based terahertz (THz)-microfluidic chip with a few arrays of asymmetric meta-atoms for the measurements of small amount of solutions. A near-field THz emission source that is locally generated in the process of optical rectification at the irradiation spot of fs laser beam induces a high-Q Fano resonance and modifies the resonance frequency of the meta-atoms when the channel between meta-atoms is filled with solutions of different concentrations. Using this chip, we successfully detected attomole order of solute in a less than 100 pL volume of the solution.