A Mesoporous Silica Film-Based Weak Measurement Sensor for Detection of Small Molecules

An improved weak measurement scheme, a weak measurement sensor with a mesoporous silica film (MSF) structure, was first proposed. A simple Stöber solution growth method was used to prepare MSF with a large surface area and high stability, which can be utilized to their mesoporous advantage during adsorption detection. The MSF-based weak measurement sensor achieved a sensitivity of 1418.8 nm/RIU and a refractive index resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.56\times 10^{-6}$ </tex-math></inline-formula> RIU. A detection limit of 53 mg/L was recorded for nonadsorbed glucose detection. In the detection of hexadecyl trimethyl ammonium bromide (CTAB), which could be physically adsorbed within the mesoporous thin-film layer, the limit of detection was significantly reduced to 12.6 nM. Heavy metal copper ions could be captured by the carboxyl complex of the MSF mesoporous layer, and a detection limit of 24.4 nM was obtained. The detection of small molecules and heavy metal ions demonstrates the high performance and great potential of MSF-based weak measurement sensors and it might be used as a versatile platform for high-sensitivity label-free optical biosensing.