Ultrawideband high density polymer-based spherical array for real-time functional optoacoustic micro-angiography

Owing to its unique ability to capture volumetric tomographic information with a single light flash, optoacoustic (OA) tomography has recently demonstrated ultrafast imaging speeds ultimately limited by the ultrasound time-of-flight. The method's scalability and the achievable spatial resolution are yet limited by the narrow bandwidth of piezo-composite arrays currently employed for OA signal detection. Here we report on the first implementation of high-density spherical array technology based on flexible polyvinylidene difluoride films featuring ultrawideband (0.3-40 MHz) sub mm² area elements, thus enabling real-time multi-scale volumetric imaging with 22-35 µm spatial resolution, superior image fidelity and over an order of magnitude signal-to-noise enhancement compared to piezo-composite equivalents. We further demonstrate five-dimensional (spectroscopic, time-resolved, volumetric) imaging capabilities by visualizing fast stimulus-evoked cerebral oxygenation changes in mice and performing real-time functional angiography of deep human micro-vasculature. The new technology thus leverages the true potential of OA for quantitative high-resolution visualization of rapid bio-dynamics across scales.