Listen to the sound of chemicals with a phononic crystal

If you’re manufacturing cosmetics, you want your products to perform with a reasonable consistency at different temperatures. To properly characterize certain properties of a fluid, one often needs specialized sensors for measuring the parameters of interest. This is the case for the temperature dependence of the many properties in methyl nonafluorobutyl ether (MNE), a chemical compound with broad commercial usage in the cosmetics industry, thanks to its non-toxic and non-flammable characteristics.

Zaremanesh et al. present the design of a phononic crystal biosensor for determining how sensitive the composition of MNE is at different temperatures. The phononic crystal sensor uses the resonance of acoustic waves as the actuating tool. As a result, the sensor can probe not only the interfacial layer between the solid resonator and the liquid, but also the entire volume, thereby inspecting the overall acoustic properties of the liquid.

The biosensor proposed by the authors uses a two-dimensional phononic crystal to monitor the acoustic properties of MNE as a function of temperature. The epoxy-filled lattice consists of hexagonally packed cylinders of tungsten rods, and empty cylinders that act as waveguides. When the empty cylinders are filled with MNE, the measurement of how soundwaves with different frequencies travel through the sensor carries information about the viscosity and mass density of MNE.

Phononic crystals are becoming an affordable alternative sensor solution in the field of chemical and biological sensors. With high-accuracy measurement of frequency resonances, such as those in periodic structures, the technique may be used for the characterization of fluids in other studies.

Source: “Temperature biosensor based on triangular lattice phononic crystals,” by Mansour Zaremanesh, Laurent Carpentier, Hamed Gharibi, Ali Bahrami, Ahmed Mehaney, Abdellatif Gueddida, Ralf Lucklum, Bahram Djafari-Rouhani, and Yan Pennec, APL Materials (2021). The article can be accessed at https://doi.org/10.1063/5.0054155 .

This paper is part of the Phononic Crystals at Various Frequencies Collection, learn more here .