High frequency ultrasound systems are in demand for medical diagnoses requiring high spatial resolution (<100 um) in disciplines such as dermatology, ophthalmology and dentistry. Key areas of research in the development of these systems are the design and fabrication of miniature arrays. Conventional microfabrication techniques impose strong dimensional constraints on the design of arrays, thereby limiting the operating frequency. Advances in the fabrication of practical devices are therefore crucial to future clinical capabilities. Major challenges are the development of fine-scale 1-3 piezocomposites and incorporating these composites into arrays. For example, a 50 MHz linear array, corresponding to imaging wavelengths around 30 um, of the same order as cellular dimensions, would have a 1-3 piezocomposite thickness of approximately 30 um, requiring ceramic pillar dimensions of around 15 um or less, and an element pitch of 30 um. In this paper, we report continuing progress in work based on design techniques and fabrication processes with the potential to produce devices operating up to 100 MHz. Advances in the net-shape micromoulding fabrication technique for the ceramic within our piezocomposites are outlined, array fabrication based on advanced surface finishing and photolithographic processes is described, and packaging options for suitable high-density electrical connections are outlined. Results from early prototype arrays operating between 30 and 50 MHz are shown, illustrating the success of the fabrication processes and their functional capabilities. Key array performance data such as electrical impedance, functional material properties, pulse-echo response and sensitivity are presented and specific potential applications in human diagnostics are discussed.