High performance integrated terahertz sensor for detection of biomolecular processes in solution

Abstract

Biomolecular processes occurring within a physiological buffer induce changes in the dielectric permittivity of the solution at terahertz frequencies (0.1–10 THz). Therefore novel high sensitivity THz sensors could potentially satisfy the need for a label‐free, immobilisation‐free, real‐time and in‐solution biosensor technology. However, the application is hindered by insufficient performance of current measurement techniques resulting in low sensitivity, low resolution, high detection limit and excessive sample volume. This work presents an integrated THz sensor topology designed to overcome the aforementioned challenges, performance evaluation with a number of typical biomolecule processes, and analysis of possible applications. The state‐of‐the‐art performance is demonstrated with room‐temperature operated solid‐state active components operating at f ≃ 0.25 THz: the sample volume is V = 4 nl, detection limit is DL <9 mg/l, sensitivity to biomolecule concentration, conformation and binding. The technology could become a versatile tool for hydration shell study, protein conformation and function analysis, concentration measurements including nucleic acid amplification by polymerase chain reaction, protein and nucleic acid binding assay.