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Photoacoustic microscopy (PAM) provides high resolution and contrast imaging of microstructures such as blood vessels and various optical contrast agents. Acoustic-resolution PAM (AR-PAM) is capable of reaching sub-centimeter of penetration depth and is optimized for tissue samples and small animals. However, the state-of-art AR-PAMs are large in size and expensive in cost, which hinders their democratization. While previous studies have focused on replacing laser sources or data acquisition devices, bulky and costly high precision linear translation stages are used to actuate the sensor to build a 3D PAM image. Here, we focused on substituting these linear translation stages with delta configuration actuators adapted from a low-cost commercially available off-the-shelf 3D printer to miniaturize the size of the system and to drastically reduce the cost. We introduce an economical PAM system that integrates the unique sensor actuation hardware and the software approach of obtaining the high-resolution image through 3D reconstruction. The preliminary phantom study demonstrated the applicability of low-cost delta configuration actuators for AR-PAM imaging.

The state-of-the-art configurations for acoustic-resolution photoacoustic (PA) microscope (AR-PAM) are large in size and expensive, hindering their democratization. While previous research on AR-PAMs introduced a low-cost light source to reduce the cost, few studies have investigated the possibility of optimizing the sensor actuation, particularly for the AR-PAM. Additionally, there is an unmet need to evaluate the image quality deterioration associated with the actuation inaccuracy. A low-cost actuation device is introduced to reduce the system size and cost of the AR-PAM while maintaining the image quality by implementing the advanced beamformers. This work proposes an AR-RAM incorporating the delta configuration actuator adaptable from a low-cost off-the-shelf 3D printer as the sensor actuation device. The image degradation due to the data acquisition positioning inaccuracy is evaluated in the simulation. We further assess the mitigation of potential actuation precision uncertainty through advanced 3D synthetic aperture focusing algorithms represented by the Delay-and-Sum (DAS) with Coherence Factor (DAS+CF) and Delay-Multiply-and-Sum (DMAS) algorithms. The simulation study demonstrated the tolerance of image quality on actuation inaccuracy and the effect of compensating the actuator motion precision error through advanced reconstruction algorithms. With those algorithms, the image quality degradation was suppressed to within 25% with the presence of 0.2 mm motion inaccuracy. The experimental evaluation using phantoms and an ex-vivo sample presented the applicability of low-cost delta configuration actuators for AR-PAMs. The measured full width at half maximum of the 0.2 mm diameter pencil-lead phantom were 0.45 ± 0.06 mm, 0.31 ± 0.04 mm, and 0.35 ± 0.07 mm, by applying the DAS, DAS+CF, and DMAS algorithms, respectively. AR-PAMs with a compact and low-cost delta configuration provide high-quality PA imaging with better accessibility for biomedical applications. The research evaluated the image degradation contributed by the actuation inaccuracy and suggested that the advanced beamformers are capable of suppressing the actuation inaccuracy.