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

Abstract

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 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 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 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 42C tissue damage limit during therapy.

A 1.25 μJ per Measurement Ultrasound Rangefinder System in 65 nm CMOS for Explorations With a Swarm of Sensor Nodes

“…PZTs typically have a nominal operating frequency spanning from a few tens of kHz to several hundreds of kHz with a relatively low bandwidth [25], [26]. Although Capacitive Micromachined Ultrasound Transducers (CMUTs) have been used in literature [27] to achieve a larger bandwidth compared to PZTs, the high-voltage DC bias requirement of CMUTs [28] is an important drawback in battery-operated applications. Accordingly, PZT1 and PZT2 are chosen as commercially available piezoelectric transducers with a nominal resonance frequency of 40 kHz and 100 kHz, and an input capacitance of 2 nF and 1 nF, respectively [29].…”

Multi-mode laser-ultrasound imaging using Time-domain Synthetic Aperture Focusing Technique (T-SAFT)

“…Ultrasonic Testing (UT) [4] has proven to be an effective tool with the advantages of low attenuation, strong penetrating ability, and high sensitivity; therefore, it has been widely used in solid defect detection. Conventional UT typically utilises piezo-electric transducers [5] for accurate displacement and phase detections, Capacitive Micromachined Ultrasonic Transducers (CMUT) [6] for array directional detection, Electromagnetic Acoustic Transducers (EMAT) [7] , [8] for metal detection, and Air-coupled Ultrasonic Transducers (ACUT) [9] for non-contact detection. Among them, piezo-electric transducers are usually used for both ultrasound excitation and detection, and acoustic couplants such as water or glycerin are always used for ultrasound transmission between the transducer and the test piece.…”

Power Efficiency Characterization with Various Gate Oxide Thicknesses in Class DE Amplifiers for HIFU Applications

“…However, this increases the gate loss (P G ) owing to the large gate voltage swing [31]. In the case of a class DE amplifier, the gate voltage swing is not limited to V DD [32]. Essentially, the gate oxide thickness affects the gate voltage swing and the overall efficiency of the power amplifier.…”