Micro-moulded randomised piezocomposites for high frequency ultrasound imaging

1-3 piezocomposites that can operate at over 30 MHz are in demand to improve spatial resolution on a sub-millimetre level for biomedical ultrasound imaging applications. However, the fabrication of such materials remains a challenge as ultrafine dimensions are required in conventional composite designs. We have previously reported the design of randomised composites to eliminate coupling to lateral modes and to relax overall dimensional constraints. In this work, practical fabrication of composites based on these designs has been realised by using a novel micro-moulding approach combining gel casting with soft lithography. Impedance spectra of randomised composites confirm their advantage for suppressing spurious modes. Pulse-echo responses of two completed transducers operating at 30 and 70 MHz have demonstrated their functional performance.