{'fraction_non_alphanumeric': 0.0225, 'fraction_numerical': 0.008125, 'mean_word_length': 5.205426356589148, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A casting-based fabrication process for a high-frequency piezo-electric linear array

Novel ultrasound arrays used in medical imaging contain many small elements (down to 100 μm) operating at high frequencies (upto tens of MHz). In such arrays, each element requires an individual electrical connection. Typically, these connections are made to soldering pads located some distance away from the transducer, which in turn are connected to the element by a pathway on a printed circuit board. However, these pathways are unshielded and therefore sensitive to electromagnetic interference and cross-talk. In this work, a casting-based fabrication process is presented where the room required for electrical connections is created vertically, i.e., in the direction perpendicular to the transducer surface. Using this process, chambers are created into which the cores of coaxial cables are inserted, and on top of these chambers the elements are built. As only the part of the cables inserted into the chambers is unshielded, the sensitivity to electromagnetic interference is strongly reduced. In addition, the elements share a single ground electrode which acts as a Faraday cage and further reduces interference. Using this fabrication process, a linear array was constructed containing eight elements of dimensions 100 μm by 350 μm operating at a center frequency of 21 MHz. The array is validated both acoustically and mechanically, and is shown to consist of eight virtually identical elements exhibiting high fractional bandwidths of more than 80%. Virtually no mechanical crosstalk is observed.