Tubular phononic crystal sensor platform for (bio)chemical liquid analysis – Tubular Bell

The project aims at a new class of phononic crystals, Tubular Phononic Crystals (TPCs) and their application as Tubular Phononic Crystal Sensor, the Tubular Bell. Our vision is a fundamentally new sensor concept for in-line monitoring of liquids in cylindrical structures like pipes (chemistry) or vessels (medicine). The physical challenge is formulation and physical description of phononic crystals created by a radical change of lattice geometry from 2D planar or 3D Cartesian with translational symmetry to 3D cylindrical with both translational and rotational symmetries. The engineering challenge is the ultimate change from chemical sensors measuring at the interface to an analyte to a new sensor class determining volumetric properties of an analyte. This novel concept will be fully explored considering fundamental interactions of acoustic fields in liquids and elastic fields in solids. Acoustic waves will be tailored so that they perturb sub-volumes of liquids in pipes or vessels revealing their physical properties. The project will deliver a platform for determination of undiscovered information behind volumetric properties due to a fundamentally new access to underlying chemical or biomedical phenomena of liquids and mixtures.
These objectives will be accomplished by means of four research lines:
1. Development of Tubular Phononic Crystals, a class of periodically structured elastic cylinders for wave propagation along the revolution axis. TPCs will constitute a completely new family of devices with geometries not considered so far in literature.
2. Investigation of advanced artificial structures to localize acoustic energy in small resonant liquid regions. This part includes the interaction between the acoustic and elastic fields at both macroscopic and microscopic scales.
3. Evolution of the Tubular Bell as new class of acoustic sensor. The phononic resonators will be deeply analyzed, considering the transduction of properties of an analyte, namely sound velocities and mass density as well as viscosity and other dissipation values, into acoustic properties of the TPC, namely resonance frequency and bandwidth of selected modes.
4. Realization of TPC and Tubular Bell prototypes for experimental proof of theoretical investigations and as demonstrator of the new sensor concept.
The target frequency resolution is 10-5 f0, striving for a sound velocity resolution <0.05 m/s.
The project requires interdisciplinary work between solid state physics, material science, microfabrication, and measurement science. Significant milestones for the project are:
(i) Demonstration of phononic band gaps in liquid-filled tubular structures.
(ii) Acoustic wave excitation, propagation, and detection in tubular structures and the coupling to resonant modes must be explored and optimized.
(iii) The relation between acoustic values and material properties and composition of liquid mixtures must be established to transfer the physical results into a measurable sensor effect.