Continuous monitoring with a permanently installed high-resolution ultrasonic phased array

Abstract

High-resolution defect detection is an integral part of non-destructive testing (NDT). Ultrasonic array transducers have been developed to respond to this need and provide high-resolution images for such applications. At present, high-resolution imaging is achieved by ultrasonic array design, such as enhanced transducer materials, and optimised element geometry to fulfil inspection requirements and miniaturise imaging artefacts, etc. This paper presents a novel ultrasonic array and controller system design strategy that can miniaturise the array and reduce manufacturing cost of the entire array system. This then enables the permanent or semi-permanent installation of arrays onto structures and long-term continuous structural health monitoring (SHM). The array geometry is designed as a compromise between the required imaging performance for the desired application and the fabrication cost for permanent installation. A prototype array transducer is constructed from piezoceramic elements bonded to a flexible printed circuit (FPC) substrate and then permanently installed on example structures to demonstrate long-term monitoring. Improved long-term sensitivity to defect growth is achieved by applying a compensation strategy for velocity and phase changes with temperature. Results show that a 5 MHz, 18-element prototype array can detect changes as small as 0.1 mm in the diameter of a side-drilled hole (SDH) defect after 3 months of continuous monitoring.

An Emerging Era: Conformable Ultrasound Electronics

“…[249] Sun et al presented the design concept on both the flexible array and controller system for a permanently installable ultrasonic array for high-resolution long-term localized monitoring of industrial structures (Figure 10j-m). [28]…”

“…Reproduced with permission. [ 28 ] Copyright 2023, The Authors, Published by SAGE Publications. g) Flexible ultrasound transceiver array for non‐invasive surface‐conformable imaging enabled by geometric phase correction.…”

“…[ 248 ] The phased array with various imaging algorithms such as plane wave imaging (PWI), synthetic aperture focusing technique (SAFT), and total focusing method (TFM), possesses the advantageous capability to provide beam steering at various angles and focalization at any desired location, hence enabling comprehensive scanning even in situations where detecting areas are limited in accessibility. [ 28 ] The time delay law governing the formation of dynamic beams is a basic principle that underlies both theoretical investigations and actual implementations of phased array technology. Conventional rigid probes are particularly advantageous for in situ inspection as they offer the greatest inspection coverage from a single detected location.…”

“…Reproduced under the terms of the Creative Commons Licensen. [ 28 ] Copyright 2023, The Authors, Published by SAGE Publications.…”

“…The concept of cUSE was first put forth before 2010, [24,25] then intensively investigated in the past six years, [26] which not only solved some current limitations of rigid and bulky ultrasound probes, but also developed various designs and technologies of conformable electronics for healthcare to a new level. In recent studies, numerous cUSE were proposed and fabricated using several fabrication strategies for NDT and biomedical applications (Figure 1), including stretchable [27] and bendable [28] devices imaging on complex surfaces, long-term monitoring with bio-adhesion [29] or intergated system, [30] large organ monitoring (breast tissue, [31] baldder volume), [32] cardiac monitoring, [33] blood pressure monitoring. [34] blood flow monitoring, [35] energy harvesting [36] and power transfer for implant device, [37] tissue repair, [38] chronic wound healing, [39] retinal stimulating, [40] peripheral nerve stimulation, [41] brain stimulation, [42] drug delivery on faces, [43] transdermal cosmeceutical delivery, [44] and several other biomedical applications.…”