Inkjet printing involves the complex interaction of mechanical, acoustic, and fluidic phenomena operating on microsecond timescales and micrometre length scales. Within a printhead, inks experience pressure oscillations approaching 100 kHz and shear rates up to 10⁶ s⁻¹: these result from nanometre-scale deformations of the ink channel walls. These conditions impose viscoelastic stresses that are not captured by conventional rheometers, which are typically limited to oscillation frequencies below 100 Hz. Consequently, many inks that have apparently identical bulk rheology may exhibit very different jetting behaviours. The TriPAV High-Frequency Rheometer was developed to bridge this gap by characterising low-viscosity fluids under realistic inkjet operating conditions. TriPAV uses solid-state piezoelectric excitation to measure the linear viscoelastic properties (G’, G”, η*) of inks and functional fluids across frequencies from 1 Hz to 10 kHz—a frequency range much closer to those encountered during waveform actuation in Drop-on-Demand (DoD) and Continuous Inkjet (CIJ) systems. The instrument completes a full frequency sweep in under five minutes using <0.1 mL of sample and operates over 5–80 °C, enabling analysis of volatile or reactive inks, UV formulations, and solvent-based coatings. In its rapid step strain Printhead Mode, the TriPAV reproduces the acoustic excitation within a printhead channel. Controlled step-strain waveforms applied via a piezo actuator, and measured by a passive sensor, yield fluid response parameters—peak amplitude, peak time, and relaxation time—that correlate directly with waveform features such as drive voltage, pulse width, and wait time. Temperature-dependent tests (20–60 °C) further identify conditions that maximise pumping efficiency, meniscus stability, and droplet reliability.