“…We have introduced the commonly applied liquid phononic crystals sensor concept, featuring a defect. Meanwhile, several reports are available, ranging from proof-of-concept and new designs or concepts [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], to consideration of experimental influences [ 38 , 39 ] and 3D printing [ 40 , 41 ], to the measurement of real samples [ 42 , 43 ]. Typical frequencies range from several hundred kHz to a few MHz, the respective dimensions of the phononic crystal from units of millimetres to 100 µm.…”