A CMUT transducer array comprising a first column (58) of spaced CMUT cells on at least one silicon island, a second column (58) of spaced CMUT cells on at least one further silicon island, the second column being staggered in alignment with the first column such that cells of the second column are partially located in spaces between successive cells of the first column, the first column and the second column being spaced apart by a gap, and a flexible foil retaining the respective silicon islands, the flexible foil comprising conductive interconnects.