Integrated HIFU Drive System on a Chip for CMUT-Based Catheter Ablation System

• Published in: IEEE transactions on biomedical circuits and systems Vol. 11; no. 3; pp. 534 - 546
• Main Authors: Farhanieh, Omid, Sahafi, Ali, Bardhan Roy, Rupak, Ergun, Arif Sanli, Bozkurt, Ayhan
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.06.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Ablation; Acoustics; Capacitive micromachined ultrasound transducer (CMUT); Catheter Ablation; catheter ablation system; Catheters; CMOS; continuous wave high-voltage driver; Damage; Electric potential; Equipment Design; Finite element method; high Intensity Focused Ultrasonic (HIFU); Humans; Integrated circuits; Medical instruments; Micromachining; Oil; Phantoms, Imaging; phase locked loop; Phase locked loops; Power consumption; Probes; Radiofrequency ablation; Real time; real-time HIFU thermal image; Sunflower oil; Temperature effects; Transducers; Ultrasonic imaging; Ultrasonography; Ultrasound; Vegetable oils; Voltage
• ISSN: 1932-4545; 1940-9990
• DOI: 10.1109/TBCAS.2017.2649942

Conventional High Intensity Focused Ultrasound (HIFU) is a therapeutic modality which is extracorporeally administered. In applications where a relatively small HIFU lesion is required, an intravascular HIFU probe can be deployed to the ablation site. In this paper, we demonstrate the design and implementation a fully integrated HIFU drive system on a chip to be placed on a 6 Fr catheter probe. An 8-element capacitive micromachined ultrasound transducer (CMUT) ring array of 2 mm diameter has been used as the ultrasound source. The driver chip is fabricated in 0.35 μm AMS high-voltage CMOS technology and comprises eight continuous-wave (CW) high-voltage CMUT drivers (10.9 ns and 9.4 ns rise and fall times at 20 V pp output into a 15 pF), an eight-channel digital beamformer (8-12 MHz output frequency with 11.25° phase accuracy) and a phase locked loop with an integrated VCO as a tunable clock source (128-192 MHz). The chip occupies 1.85 × 1.8 mm 2 area including input and output (I/O) pads. When the transducer array is immersed in sunflower oil and driven by the IC with eight 20 V pp CW pulses at 10 MHz, real-time thermal images of the HIFU beam indicate that the focal temperature rises by 16.8 °C in 11 seconds. Each HV driver consumes around 67 mW of power when driving the CMUT array at 10 MHz, which adds up to 560 mW for the whole chip. FEM based analysis reveals that the outer surface temperature of the catheter is expected to remain below the 42 °C tissue damage limit during therapy.