Abstract
An all-optical ultrasound probe for vascular tissue imaging was developed. Ultrasound was generated by pulsed laser illumination of a functionalized carbon nanotube composite coating on the end face of an optical fiber. Ultrasound was detected with a Fabry-Pérot (FP) cavity on the end face of an adjacent optical fiber. The probe diameter was < 0.84 mm and had an ultrasound bandwidth of ~20 MHz. The probe was translated across the tissue sample to create a virtual linear array of ultrasound transmit/receive elements. At a depth of 3.5 mm, the axial resolution was 64 µm and the lateral resolution was 88 µm, as measured with a carbon fiber target. Vascular tissues from swine were imaged ex vivo and good correspondence to histology was observed.
Highlights
High frequency, miniature ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures such as coronary stent placement and cardiac ablation [1,2]
We describe a novel miniature fiber optic probe that is based on the two concepts outlined above: a fiber optic transmitter that employs a carbon nanotubes (CNTs) based absorbing film [12] for generating broadband ultrasound and a fiber-optic FP polymer sensor [21] for receiving it
The xylene decreased the viscosity of the PDMS, and the functionalization allowed for uniform dispersion of CNTs in xylene
Summary
Miniature ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures such as coronary stent placement and cardiac ablation [1,2]. In current-generation ultrasound probes, ultrasound is typically generated and received electrically using piezoelectric [3] or capacitive micromachined transducers [4]. Mechanically dicing and electrically connectorizing piezoelectric elements can become challenging as their dimensions become smaller and the ultrasound frequencies become higher. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts [5,6,7,8]. They offer several distinguishing advantages including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution endoscopic imaging. Optical methods that employ optical fibers for ultrasound transmission and reception can
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