Polymer-based ultrawideband transducers for high resolution hemispherical optoacoustic tomography

Sep 28, 2026

Uploaded by Liam

Existing transducers fall short for high-performance hemispherical optoacoustic tomography due to insufficient ultrawide bandwidth, suboptimal impedance matching that increases reverberation artifacts, and limited ability to form non-flat geometries. PVDF can meet these requirements in principle, yet it has known weaknesses. This work highlights how PVDF challenges can be overcome in a high-performance PVDF-based hemispherical system for ultrawideband functional optoacoustic tomography, addressing key limits of ultrasound-designed receivers.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages4

Reading Time10 min

AccessFree to download

Abstract

Design criteria and limitations

Why ultrasound transducers underperform for optoacoustic imaging

PVDF advantages and shortcomings

Siegel et al. Light: Science & Applications (2026)15:3 [www.nature.com/lsa](www.nature.com/lsa) [https://doi.org/10.1038/s41377-025-02101-8](https://doi.org/10.1038/s41377-025-02101-8) NEWS & VIEWS Open Access Polymer-based ultrawideband transducers for high resolution hemispherical optoacoustic tomography Amanda P. Siegel1, Rayyan Manwar1 and Kamran Avanaki1,2,3 ✉ Abstract Available transducers do not fulﬁll all of the necessary design criteria for high-performance hemispherical optoacoustic tomography, namely: an ultrawide bandwidth in order to acquire the full range of optoacoustic emissions from targets of interest, good impedance matching to minimize reverberation artifacts, and a modiﬁable form factor, for inclusion in non-ﬂat geometries. Polyvinylidene ﬂuoride (PVDF) transducers can, in principle, meet all of these criteria, but PVDF has known shortcomings. In Ultrawideband high-density polymer-based spherical array for functional optoacoustic microangiography, all of the challenges of working with PVDF are overcome with the demonstration of a high-performance PVDF-based hemispherical optoacoustic tomographic system. There is a growing recognition that one major roadblock to improving optoacoustic (OA) imaging performance is the limited capabilities of existing transducers. These transducers were most often designed for ultrasound (US) imaging, which has a different set of requirements than OA imaging, where transducers operate only in receiver mode. First, US transducers must have high electromechanical coupling efﬁciency to be able to generate strong, consistent acoustic signals. However, because OA imaging does not rely on transducergenerated acoustic waves, this property is not relevant for OA imaging. Second, in US imaging, the signal received will have a very similar bandwidth as the signal generated, so there is no strong need for wideband transducers. However, because OA signals are generated by the thermoelastic effect, there is no limitation on how wide a frequency range they can encompass. Third, in US imaging, although reverberations should be minimized as they reduce overall signal strength, because the transmitted signal is known, it is possible to utilize developed, effective methods for reducing the impact of reverberations (active control, pulse sequencing, time gating, and Correspondence: Kamran Avanaki ([avanaki@uic.edu](avanaki@uic.edu)) 1Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, IL, USA 2Section of Neonatology, Department of Pediatrics, UI Health Children’s Hospital of the University of Illinois at Chicago, Chicago, IL, USA Full list of author information is available at the end of the article established correction methods). However, because OA imaging generates weaker signals and cannot use transmission-matching techniques for reducing reverberation effects, it has a greater need to reduce or eliminate reverberations (i.e. improve transducer/tissue impedance matching). OA imaging is typically limited to using ultrasound (US) transducers, not because they are ideal, but because they are the most readily available option. But what if an OA tomographic system were designed with transducers optimized for OA imaging rather than US imaging? How much would this impact OA image reconstruction? The core materials for ultrasound transducers are either piezo-ceramics or piezo-polymers. Polyvinylidene ﬂuoride (PVDF) is a ferroelectric polymer that was ﬁrst recognized to have strong piezoelectric properties over 50 years ago1. PVDF-based transducers can detect a wide range of frequencies (up to 70 MHz or more) with an extremely wide bandwidth (>100%). Their mechanical ﬂexibility allows them to be fabricated in various shapes and curvatures. Their impedance (around ~4 MRayl) is much closer to tissue (~1.5 MRayl) than typical piezoceramic transducers (lead zirconate titanate (PZT) has impedance of ~33 MRayl), which gives PVDF

FAQs

What design criteria limit existing transducers for hemispherical optoacoustic tomography?

They lack ultrawide bandwidth to capture the full optoacoustic emission range, they provide poor impedance matching that increases reverberation artifacts, and they offer limited form-factor flexibility for non-flat geometries.

Why are ultrasound-optimized transducers not ideal for optoacoustic receiver-mode imaging?

Ultrasound transducers are designed for transmitting strong signals with electromechanical coupling and for bandwidth requirements tied to generated and received signals; optoacoustic imaging generates signals via the thermoelastic effect and needs different impedance behavior to reduce reverberations.

How do PVDF transducers help address optoacoustic requirements despite their drawbacks?

PVDF offers very wide bandwidth, mechanical flexibility for curved shapes, and impedance closer to tissue, improving reception sensitivity and reducing reverberation artifacts; however, it can be mechanically/thermally fragile and may require specialized electronics due to lower capacitance and lower coupling.

Sep 28, 2026

Uploaded by Liam