Associated IDTs in surface acoustic wave devices for closed-loop control inkjet system

This paper presents a novel associated interdigital transducers (A-IDTs) on Y-Z Lithium Niobate (LiNbO₃) for detecting ink pressure at the nozzle during droplet generation. The device is composed of transmitter IDTs with arcs (D_a = 100⁰) of concentric circles and conventional receiver IDTs with straight fingers. The nozzle orifice is etched through the wafer and is perpendicular to the surface acoustic wave (SAW) propagation path. Compared to conventional focused SAW devices, the proposed SAW device, which includes spectral content of the mechanical waves, output magnitude and attenuation per acoustic length unit due to the effect of flow rate at the nozzle orifice, is more effective. The advantages of the A-IDT structure include focused properties due to the input focused fingers and IDT fabrication simplification. Electrical and mechanical characteristic analysis is presented to determine the relation between ink pressure and output potential. The ink droplet is separated after the second pitch appearance of the output signal in the frequency-time domain.