Straalsturing en -regeling van grootvlakkige ultrasone actuatorarrays voor haptische perceptie

The advent of micro-electromechanical system (MEMS) device fabrication technologies has since enabled a variety of novel applications across many domains. Recent developments in ultrasound MEMS in the form of capacitive (cMUT) and piezoelectric micromachined ultrasound transducers (pMUT) allows for the miniaturisation of traditionally large ultrasound devices. In particular, air-coupled ultrasound MEMS arrays are an attractive alternative to the bulk transducer arrays used in ultrasound mediated mid-air vibrotactile haptic feedback applications exhibiting advantages in array sizes, fill-factor, and power efficiency. This work presents foundational work aimed towards enabling the generation of vibrotactile haptic holograms in mid-air using beamsteerable phased arrays of large area thin-film polymer-based pMUTs, approached from both a device and system level perspective. First, the large area polymeric pMUT device characteristics were described using electromechanical lumped circuit element modelling, incorporating a novel contribution approximating the influence of the elastic boundary conditions, used for predictive modelling and optimisation of devices in array-wide simulations. Second, array design considerations were investigated through the fabrication and analysis of pMUT annular arrays generating high pressure foci in air. Additionally, limited beamsteering capabilities of row-column addressed passively driven rectilinear pMUT arrays were demonstrated using an iterative phase-retrieval method. Finally, active pMUT array driving strategies limited to the generation of a single beamsteerable acoustic focus were evaluated, including a novel mixer-based quadratic-programming approach allowing for reduced channel (N2 → 2N) phase-shift mapping of rectilinear row-column addressed arrays, enabling efficient and effective control towards the generation of vibrotactile haptic holograms in air.