IntroductionUltrasound systems traditionally increase sample area or resolution by increasing the number of elements (1) , with a corresponding increase in the physical and electrical complexity of such systems. By adopting a different approach of using generic building blocks of 2D elements, coupled to associated electronics, a full 3D volume can be sampled from a single point allowing fast and accurate image collection with greater sample area or enhanced resolution obtainable by increasing the number of modules in use.Due to dimensional constraints it is increasingly common for portable hand-held array-based NDT systems to have electronics in close proximity to the transducer array. Impedance matching between transducers and electronics can be hard to achieve and retain in a practical system. Cumulative impedance mismatches over time between the electronics and the individual transducers can greatly impair the signal-to-noise ratio. One possible solution lies with the avoidance of cables. Previous solutions aimed at integrating the transducer and associated electronics, usually on the same silicon substrate, have resulted in very closely coupled designs which can limit the flexibility should it be desirable to modify the array configuration to suit a particular application. This paper presents, as an alternative, the concept of a modular ultrasonic imaging system utilising generic building blocks of 2D array element configurations to construct low-cost ultrasonic array systems of any size and shape, resulting in a fully scalable solution without requiring redesign. This system can be seen as a mosaic consisting of multiple tiles which can be tessellated to form reconfigurable arrays of any size and shape.Each module, or tile, integrates a 16-element piezocomposite transducer array in a 4 × 4 matrix together with the analogue electronics necessary for full transmit-receive capability on all 16 channels, thus resolving the scaling difficulties that exist due to corresponding increases in quantity and complexity of transmission and reception electronics (1,2) . Unlike traditional ultrasonic systems, the drive electronics are situated adjacent to the sensor head to eliminate the use of long cables and hence minimise parasitic capacitances that degrade the strength of the received signal (1) which is of prime importance to enable low-voltage excitation.The ability to form ultrasound systems in this way, from generic building blocks which are physically identical for manufacturing purposes yet functionally unique via programming to suit the application, has the potential to transform ultrasonic NDT with arrays as it would permit the functionality of off-the-shelf hardware to be tailored to suit any given target application (3) in a field where equipment has traditionally been highly application-specific, a point increasingly considered in research in ultrasonics (4) . The next section provides more information on the basic concept and its potential applications. This is followed by more detailed technical informati...