An electronically-scanned CMUT-in-CMOS transducer for hemodialysis vascular access monitoring

Frequent surveillance of vascular access health is essential for reducing complications in hemodialysis treatment for end-stage renal disease. Ultrasound-based volume flow monitoring techniques are a promising solution, however challenges must be overcome to reduce operator dependence and to create compact monitoring modules that do not impede dialysis treatment. This paper presents a 120-element capacitive micromachined ultrasonic transducer (CMUT) array that uses on-array switches and analog circuits to enable digital control over the size and position of a single-output cluster of elements. This allows the cluster to be electronically moved during treatment to maintain a high quality Doppler signal without physical intervention. The array is fabricated using the CMUT-in-CMOS approach, whereby complex ultrasound arrays with integrated electronics can be manufactured extremely affordably, opening the door to using such arrays for a variety of cost-sensitive applications.