Fluidic self-assembly for MicroLED displays by controlled viscosity.

Displays in which arrays of microscopic 'particles', or chiplets, of inorganic light-emitting diodes (LEDs) constitute the pixels, termed MicroLED displays, have received considerable attention1,2 because they can potentially outperform commercially available displays based on organic LEDs3,4 in terms of power consumption, colour saturation, brightness and stability and without image burn-in issues1,2,5-7. To manufacture these displays, LED chiplets must be epitaxially grown on separate wafers for maximum device performance and then transferred onto the display substrate. Given that the number of LEDs needed for transfer is tremendous-for example, more than 24 million chiplets smaller than 100 µm are required for a 50-inch, ultra-high-definition display-a technique capable of assembling tens of millions of individual LEDs at low cost and high throughput is needed to commercialize MicroLED displays. Here we demonstrate a MicroLED lighting panel consisting of more than 19,000 disk-shaped GaN chiplets, 45 µm in diameter and 5 µm in thickness, assembled in 60 s by a simple agitation-based, surface-tension-driven fluidic self-assembly (FSA) technique with a yield of 99.88%. The creation of this level of large-scale, high-yield FSA of sub-100-µm chiplets was considered a significant challenge because of the low inertia of the chiplets. Our key finding in overcoming this difficulty is that the addition of a small amount of poloxamer to the assembly solution increases its viscosity which, in turn, increases liquid-to-chiplet momentum transfer. Our results represent significant progress towards the ultimate goal of low-cost, high-throughput manufacture of full-colour MicroLED displays by FSA.

Recent Advances in Contrast-Enhanced Photoacoustic Imaging: Overcoming the Physical and Practical Challenges.

For decades now, photoacoustic imaging (PAI) has been investigated to realize its potential as a niche biomedical imaging modality. Despite its highly desirable optical contrast and ultrasonic spatiotemporal resolution, PAI is challenged by such physical limitations as a low signal-to-noise ratio (SNR), diminished image contrast due to strong optical attenuation, and a lower-bound on spatial resolution in deep tissue. In addition, contrast-enhanced PAI has faced practical limitations such as insufficient cell-specific targeting due to low delivery efficiency and difficulties in developing clinically translatable agents. Identifying these limitations is essential to the continuing expansion of the field, and substantial advances in developing contrast-enhancing agents, complemented by high-performance image acquisition systems, have synergistically dealt with the challenges of conventional PAI. This review covers the past four years of research on pushing the physical and practical challenges of PAI in terms of SNR/contrast, spatial resolution, targeted delivery, and clinical application. Promising strategies for dealing with each challenge are reviewed in detail, and future research directions for next generation contrast-enhanced PAI are discussed.

Wide-field three-dimensional photoacoustic/ultrasound scanner using a two-dimensional matrix transducer array.

Two-dimensional matrix transducer arrays are the most appropriate imaging probes for acquiring dual-modal 3D photoacoustic (PA)/ultrasound (US) images. However, they have small footprints which limit the field-of-view (FOV) to less than 10 mm × 10 mm and degrade the spatial resolution. In this study, we demonstrate a dual-modal PA and US imaging system (using a 2D matrix transducer array and a motorized 2D scanning system) to enlarge the FOV of volumetric images. Multiple PA volumes were merged to form a wide-field image of approximately 45 mm × 45 mm. In vivo imaging was demonstrated using rat sentinel lymph nodes (SLNs) and bladders stained with methylene blue. We believe that this volumetric PA/US imaging technique with a 2D matrix transducer array can be a useful tool for narrow-field real-time monitoring and wide-field imaging of various preclinical and clinical studies.

Toll-Like Receptor 5 Promotes the Neurogenesis From Embryonic Stem Cells and Adult Hippocampal Neural Stem Cells in Mice.

Toll-like receptors (TLRs) make a crucial contribution to the innate immune response. TLR5 was expressed in embryoid body derived from mouse embryonic stem cells (mESCs) and ßIII-tubulin-positive cells under all-trans retinoic acid-treated condition. TLR5 was upregulated during neural differentiation from mESCs and augmented the neural differentiation of mESCs via nuclear factor-κB and interleukin 6/CREB pathways. Besides, TLR5 was expressed in SOX2- or doublecortin-positive cells in the subgranular zone of the hippocampal dentate gyrus where adult neurogenesis occurs. TLR5 inhibited the proliferation of adult hippocampal neural stem cells (NSCs) by regulating the cell cycle and facilitated the neural differentiation from the adult hippocampal NSCs via JNK pathway. Also, TLR5 deficiency impaired fear memory performance in mice. Our data suggest that TLR5 is a crucial modulator of neurogenesis from mESCs and adult hippocampal NSCs in mice and represents a new therapeutic target in neurological disorders related to cognitive function.

Belzutifan (MK-6482): Biology and Clinical Development in Solid Tumors.

PURPOSE OF REVIEW: To review the biology, drug development, and clinical data regarding the efficacy and safety of belzutifan (MK-6482), a small molecule inhibitor of HIF-2α. RECENT FINDINGS: Belzutifan, a second-generation HIF-2α inhibitor, was shown to provide clinically meaningful benefit in the treatment of VHL-associated tumors (including ccRCC, pancreatic lesions as well as neuroendocrine tumor, and CNS hemangioblastomas). The recommended dose of belzutifan is 120 mg orally daily and half-life is 14 h. In pretreated ccRCC, belzutifan achieved disease control rate of 80% in phase I trial. The most common side effects include anemia and hypoxia related symptoms. Investigation into the important role HIF-2α plays in the expression of genes associated with angiogenesis, erythropoiesis, carcinogenesis, and progression of tumors and the discovery of structural vulnerability within HIF-2α have resulted in the development of a new therapy that has demonstrated efficacy and safety in recent clinical trials. Further research is ongoing to optimize therapeutic benefits from this new exciting therapeutic modality and to improve the outcome of HIF-2α-driven tumors.

Association Between Internet Searches Related to Suicide/Self-harm and Adolescent Suicide Death in South Korea in 2016-2020: Secondary Data Analysis.

BACKGROUND: Previous studies have investigated the association between suicide and internet search volumes of terms related to suicide or self-harm. However, the results varied by people's age, period, and country, and no study has exclusively investigated suicide or self-harm rates among adolescents. OBJECTIVE: This study aims to determine the association between the internet search volumes of terms related to suicide/self-harm and the number of suicides among South Korean adolescents. We investigated gender differences in this association and the time lag between the internet search volumes of the terms and the connected suicide deaths. METHODS: We selected 26 search terms related to suicide and self-harm among South Korean adolescents, and the search volumes of these terms for adolescents aged 13-18 years were obtained from the leading internet search engine in South Korea (Naver Datalab). A data set was constructed by combining data from Naver Datalab and the number of suicide deaths of adolescents on a daily basis from January 1, 2016, to December 31, 2020. Spearman rank correlation and multivariate Poisson regression analyses were performed to identify the association between the search volumes of the terms and the suicide deaths during that period. The time lag between suicide death and the increasing trend in the search volumes of the related terms was estimated from the cross-correlation coefficients. RESULTS: Significant correlations were observed within the search volumes of the 26 terms related to suicide/self-harm. The internet search volumes of several terms were associated with the number of suicide deaths among South Korean adolescents, and this association differed by gender. The search volume for "dropout" showed a statistically significant correlation with the number of suicides in all adolescent population groups. The correlation between the internet search volume for "dropout" and the connected suicide deaths was the strongest for a time lag of 0 days. In females, self-harm and academic score showed significant associations with suicide deaths, but academic score showed a negative correlation, and the time lags with the strongest correlations were 0 and -11 days, respectively. In the total population, self-harm and suicide method were associated with the number of suicides, and the time lags with the strongest correlations were +7 and 0 days, respectively. CONCLUSIONS: This study identifies a correlation between suicides and internet search volumes related to suicide/self-harm among South Korean adolescents, but the relatively weak correlation (incidence rate ratio 0.990-1.068) should be interpreted with caution.

Radiographic rotational profiles of the proximal and distal humerus: analysis of 46 computed tomography scans with 3-dimensional simulation.

BACKGROUND: To date, no study has investigated the radiographic rotational profiles (RRPs) of the proximal and distal humerus. However, malrotation after minimally invasive surgery for humeral fracture has been an unsolved problem. Therefore, we aimed to investigate the RRPs of the proximal and distal humerus that linearly correlate with rotational status and show significant differences as the rotational status changes. METHODS: Forty-six computed tomography scans of the humerus were 3-dimensionally reconstructed, and 5 rotational statuses (20° and 10° of internal rotation; neutral; and 10° and 20° of external rotation) were simulated. Seven candidate RRPs of the proximal humerus and 4 candidates of the distal humerus were measured for each rotational status. The overall differences and trends in the RRPs as the rotational status changed were evaluated, and multiple comparisons were performed between the RRPs for each of the 5 rotational statuses. Moreover, the correlations between the RRPs and rotational status with adjustment of retroversion were analyzed. Finally, interobserver and intraobserver reliabilities were evaluated. RESULTS: The following proximal and distal RRPs were linearly correlated with rotational status, differed significantly between the rotational statuses, and showed a relatively low prediction error and excellent interobserver and intraobserver reliabilities: the distance from the tip of the lesser tuberosity to the lateral margin of the proximal humerus (PL1) and the medial margin of the head (PL2), as well as the PL1 to PL2 ratio (PRL), in the proximal humerus; and the distance from the medial margin of the olecranon process to the medial epicondyle (DOP), the widest width of the overlapped olecranon fossa (DOF), and the distance from the lateral margin of the capitellum to the lateral epicondyle (DC) in the distal humerus. CONCLUSION: Our findings suggest that PL1, PL2, and PRL in the proximal humerus and DOP, DOF, and DC in the distal humerus are potentially useful and reproducible RRPs for restoring the intrinsic rotational alignment in humeral fractures.

Parallelized Particle Swarm Optimization on FPGA for Realtime Ballistic Target Tracking.

This paper addresses the problem of tracking a high-speed ballistic target in real time. Particle swarm optimization (PSO) can be a solution to overcome the motion of the ballistic target and the nonlinearity of the measurement model. However, in general, particle swarm optimization requires a great deal of computation time, so it is difficult to apply to realtime systems. In this paper, we propose a parallelized particle swarm optimization technique using field-programmable gate array (FPGA) to be accelerated for realtime ballistic target tracking. The realtime performance of the proposed method has been tested and analyzed on a well-known heterogeneous processing system with a field-programmable gate array. The proposed parallelized particle swarm optimization was successfully conducted on the heterogeneous processing system and produced similar tracking results. Also, compared to conventional particle swarm optimization, which is based on the only central processing unit, the computation time is significantly reduced by up to 3.89×.

Three-dimensional Multistructural Quantitative Photoacoustic and US Imaging of Human Feet in Vivo.

Background Monitoring the microcirculation in human feet is crucial in assessing peripheral vascular diseases, such as diabetic foot. However, conventional imaging modalities are more focused on diagnosis in major arteries, and there are limited methods to provide microvascular information in early stages of the disease. Purpose To investigate a three-dimensional (3D) noncontrast bimodal photoacoustic (PA)/US imaging system that visualizes the human foot morphologically and also reliably quantifies podiatric vascular parameters noninvasively. Materials and Methods A clinically relevant PA/US imaging system was combined with a foot scanner to obtain 3D PA and US images of the human foot in vivo. Healthy participants were recruited from September 2020 to June 2021. The collected 3D PA and US images were postprocessed to present structural information about the foot. The quantitative reliability was evaluated in five repeated scans of 10 healthy feet by calculating the intraclass correlation coefficient and minimal detectable change, and the detectability of microvascular changes was tested by imaging 10 healthy feet intentionally occluded with use of a pressure cuff (160 mm Hg). Statistically significant difference is indicated with P values. Results Ten feet from six healthy male volunteers (mean age ± standard deviation, 27 years ± 3) were included. The foot images clearly visualized the structure of the vasculature, bones, and skin and provided such functional information as the total hemoglobin concentration (HbT), hemoglobin oxygen saturation (SO2), vessel density, and vessel depth. Functional information from five independent measurements of 10 healthy feet was moderately reliable (intraclass correlation coefficient, 0.51-0.74). Significant improvements in HbT (P = .006) and vessel density (P = .046) as well as the retention of SO2 were observed, which accurately described the microvascular change due to venous occlusion. Conclusion Three-dimensional photoacoustic and US imaging was able to visualize morphologic and physiologic features of the human foot, including the peripheral microvasculature, in healthy volunteers. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Mezrich in this issue.

Hyaluronate-Black Phosphorus-Upconversion Nanoparticle Complex for Non-invasive Theranosis of Skin Cancer.

Despite the wide investigation on black phosphorus (BP) for biophotonic applications, the finite depth of light penetration has limited further development of BP-based photomedicines. Here, we developed a hyaluronate-BP-upconversion nanoparticle (HA-BP-UCNP) complex for near-infrared (NIR) light-mediated multimodal theranosis of skin cancer with photoacoustic (PA) bioimaging, photodynamic therapy (PDT), and photothermal therapy (PTT). In contrast to the conventional BP-based skin cancer theranosis, the HA-BP-UCNP complex could be non-invasively delivered into the tumor tissue to induce the cancer cell apoptosis upon NIR light irradiation. The PA imaging of BP successfully visualized the non-invasive transdermal delivery of the HA-BP-UCNP complex into the mice skin. HA in the complex facilitated the transdermal delivery of BP into the tumor tissue under the skin. Upon 980 nm NIR light irradiation, the UCNP converted the light to UV-blue light to generate reactive oxygen species by sensitizing BP in the HA-BP-UCNP complex for PDT. Remarkably, 808 nm NIR irradiation with PTT triggered the apoptosis of tumor cells. Taken together, we could confirm the feasibility of the HA-BP-UCNP complex for NIR light-mediated multimodal theranosis of skin cancers.

Overcoming barriers in photodynamic therapy harnessing nano-formulation strategies.

Photodynamic therapy (PDT) has been extensively investigated for decades for tumor treatment because of its non-invasiveness, spatiotemporal selectivity, lower side-effects, and immune activation ability. It can be a promising treatment modality in several medical fields, including oncology, immunology, urology, dermatology, ophthalmology, cardiology, pneumology, and dentistry. Nevertheless, the clinical application of PDT is largely restricted by the drawbacks of traditional photosensitizers, limited tissue penetrability of light, inefficient induction of tumor cell death, tumor resistance to the therapy, and the severe pain induced by the therapy. Recently, various photosensitizer formulations and therapy strategies have been developed to overcome these barriers. Significantly, the introduction of nanomaterials in PDT, as carriers or photosensitizers, may overcome the drawbacks of traditional photosensitizers. Based on this, nanocomposites excited by various light sources are applied in the PDT of deep-seated tumors. Modulation of cell death pathways with co-delivered reagents promotes PDT induced tumor cell death. Relief of tumor resistance to PDT with combined therapy strategies further promotes tumor inhibition. Also, the optimization of photosensitizer formulations and therapy procedures reduces pain in PDT. Here, a systematic summary of recent advances in the fabrication of photosensitizers and the design of therapy strategies to overcome barriers in PDT is presented. Several aspects important for the clinical application of PDT in cancer treatment are also discussed.

GPU-Accelerated PD-IPM for Real-Time Model Predictive Control in Integrated Missile Guidance and Control Systems.

This paper addresses the problem of real-time model predictive control (MPC) in the integrated guidance and control (IGC) of missile systems. When the primal-dual interior point method (PD-IPM), which is a convex optimization method, is used as an optimization solution for the MPC, the real-time performance of PD-IPM degenerates due to the elevated computation time in checking the Karush-Kuhn-Tucker (KKT) conditions in PD-IPM. This paper proposes a graphics processing unit (GPU)-based method to parallelize and accelerate PD-IPM for real-time MPC. The real-time performance of the proposed method was tested and analyzed on a widely-used embedded system. The comparison results with the conventional PD-IPM and other methods showed that the proposed method improved the real-time performance by reducing the computation time significantly.

Growth Properties of Carbon Nanowalls on Nickel and Titanium Interlayers.

This research is conducted in order to investigate the structural and electrical characteristics of carbon nanowalls (CNWs) according to the sputtering time of interlayers. The thin films were deposited through RF magnetron sputtering with a 4-inch target (Ni and Ti) on the glass substrates, and the growth times of the deposition were 5, 10, and 30 min. Then, a microwave plasma-enhanced chemical vapor deposition (PECVD) system was used to grow CNWs on the interlayer-coated glass substrates by using a mixture of H2 and CH4 gases. The FE-SEM analysis of the cross-sectional and planar images confirmed that the thickness of interlayers linearly increased according to the deposition time. Furthermore, CNWs grown on the Ni interlayer were taller and denser than those grown on the Ti interlayer. Hall measurement applied to measure sheet resistance and conductivity confirmed that the electrical efficiency improved significantly as the Ni or Ti interlayers were used. Additionally, UV-Vis spectroscopy was also used to analyze the variations in light transmittance; CNWs synthesized on Ni-coated glass have lower average transmittance than those synthesized on Ti-coated glass. Based on this experiment, it was found that the direct growth of CNW was possible on the metal layer and the CNWs synthesized on Ni interlayers showed outstanding structural and electrical characterizations than the remaining interlayer type.

Red cell manufacturing using parallel stirred-tank bioreactors at the final stages of differentiation enhances reticulocyte maturation.

The aim of this study was to develop a robust, quality controlled, and reproducible erythroid culture system to obtain high numbers of mature erythroblasts and red blood cells (RBCs). This was achieved using a fully controlled stirred-tank bioreactor by the design of experiments (DOE) methods in the serum-free medium by defining the appropriate culture parameters. Human cord blood CD34+ cells were first cultured in static flasks and then inoculated to stirred-tank bioreactors. Cell diameter was gradually decreased and final RBC yields were significantly higher when cells were inoculated at sizes smaller than 12 µm. The larger immature cells in the basophilic stage did not survive, while smaller mature erythroid cells were successfully expanded at high agitation speeds, demonstrating that appropriate seeding timing is critical. A high inoculation cell density of 5 × 106 cells/ml was achieved reaching 1.5 × 107 cells/ml. By using DOE analysis fitted to precise stages of erythropoiesis, we were able to acquire the optimal culture parameters for pH (7.5), temperature (37°C), dissolved oxygen, agitation speed (500 rpm), inoculation timing (cell diameter 12-13 µm), media feeding regimen, and cell seeding density (5 × 106 cells/ml). The final pure RBCs showed appropriate functions compared with fresh donor RBCs, confirming that manufacturing mature RBCs with reproducibility is possible.

Emerging combination strategies with phototherapy in cancer nanomedicine.

Optical techniques using developed laser and optical devices have made a profound impact on modern medicine, with "biomedical optics" becoming an emerging field. Sophisticated technologies have been developed in cancer nanomedicine, such as photothermal therapy and photodynamic therapy, among others. However, single-mode phototherapy cannot completely treat persistent tumors, with the challenges of relapse or metastasis remaining; therefore, combinatorial strategies are being developed. In this review, the role of light in cancer therapy and the challenges of phototherapy are discussed. The development of combinatorial strategies with other therapeutic methods, including chemotherapy, immunotherapy, gene therapy, and radiotherapy, is presented and future directions are further discussed. This review aims to highlight the significance of light in cancer therapy and discuss the combinatorial strategies that show promise in addressing the challenges of phototherapy.

Preparation of Carbon Nanowall and Carbon Nanotube for Anode Material of Lithium-Ion Battery.

Carbon nanowall (CNW) and carbon nanotube (CNT) were prepared as anode materials of lithium-ion batteries. To fabricate a lithium-ion battery, copper (Cu) foil was cleaned using an ultrasonic cleaner in a solvent such as trichloroethylene (TCE) and used as a substrate. CNW and CNT were synthesized on Cu foil using plasma-enhanced chemical vapor deposition (PECVD) and water dispersion, respectively. CNW and CNT were used as anode materials for the lithium-ion battery, while lithium hexafluorophosphate (LiPF6) was used as an electrolyte to fabricate another lithium-ion battery. For the structural analysis of CNW and CNT, field emission scanning electron microscope (FE-SEM) and Raman spectroscopy analysis were performed. The Raman analysis showed that the carbon nanotube in composite material can compensate for the defects of the carbon nanowall. Cyclic voltammetry (CV) was employed for the electrochemical properties of lithium-ion batteries, fabricated by CNW and CNT, respectively. The specific capacity of CNW and CNT were calculated as 62.4 mAh/g and 49.54 mAh/g. The composite material with CNW and CNT having a specific capacity measured at 64.94 mAh/g, delivered the optimal performance.

Protein arginine methyltransferase-1 stimulates dopaminergic neuronal cell death in a Parkinson's disease model.

Recent studies have revealed that protein arginine methyltransferases (PRMTs) are responsible for diverse neurodegenerative diseases. However, their pathophysiological role in dopaminergic neuronal death in Parkinson's disease (PD) has not been evaluated. In this study, we demonstrated that 1-Methyl-4-phenylpyridinium iodide (MPP+), rotenone and paraquat, which cause dopaminergic neuronal cell death, increased PRMT1 expression in dopaminergic cell line. Dopaminergic neuronal cell death was increased by PRMT1 overexpression. MPP+-induced cell death was attenuated by PRMT1 knockdown. Poly (ADP-ribose) polymerase-1 (PARP1) expression and activity, poly-ADP-ribosylation (PARylation), were elevated by MPP+. Moreover, we found that PRMT1 positively regulates nuclear translocation of apoptosis-inducing factor (AIF). Elevated PRMT1 expression was observed in the substantia nigra pars compacta of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-injected mice. Furthermore, MPTP-induced dopaminergic neuronal death was reduced in PRMT1 haploinsufficient (prmt1+/-) mice. These data suggest that PRMT1 is implicated in PARP1/AIF-mediated dopaminergic neuronal cell death, which might be involved in the pathology of PD. Therefore, our results propose PRMT1 as a new target to develop a potential treatment of PD.

Color reproduction pipeline for an RGBW color filter array sensor.

Many types of RGBW color filter array (CFA) have been proposed for various purposes. Most studies utilize white pixel intensity for improving the signal-to-noise ratio of the image and demosaicing the image, but we note that the white pixel intensity can also be utilized to improve color reproduction. In this paper, we propose a color reproduction pipeline for RGBW CFA sensors based on a fast, accurate, and hardware-friendly gray pixel detection using white pixel intensity. The proposed color reproduction pipeline was tested on a dataset captured from an OPA sensor which has RGBW CFA. Experimental results show that the proposed pipeline estimates the illumination more accurately and preserves the achromatic color better than conventional methods which do not use white pixel intensity.

Nonlinear pth root spectral magnitude scaling beamforming for clinical photoacoustic and ultrasound imaging.

A recently introduced nonlinear pth root delay-and-sum (NL-p-DAS) beamforming (BF) technique for ultrasound (US) and photoacoustic (PA) imaging, achieving better spatial and contrast resolution compared to a conventional delay and sum (DAS) technique. While the method is advantageous for better resolution, it suffers from grainy speckles and dark areas in the image mainly due to the interference of non-sinusoidal functions. In this Letter, we introduce a modified NL-p-DAS technique called nonlinear pth root spectral magnitude scaling (NL-p-SMS), which performs the pth root on the spectral magnitude instead of the temporal amplitude. We evaluated the US and PA images of NL-p-SMS against those of NL-p-DAS by comparing the axial and lateral line profiles, contrasts, and contrast-to-noise ratios (CNRs) in both phantom and in vivo imaging studies with various p values. As a result, we found that the NL-p-SMS has better axial resolution and CNR than the NL-p-DAS, and reduces the grainy speckles and dark area artifacts. We believe that, with this enhanced performance, our proposed approach could be an advancement compared to the existing nonlinear BF algorithms.

In Vivo Dual-Modal Photoacoustic and Ultrasound Imaging of Sentinel Lymph Nodes Using a Solid-State Dye Laser System.

Photoacoustic imaging (PAI) is being actively investigated as a non-invasive and non-radioactive imaging technique for sentinel lymph node (SLN) biopsy. By taking advantage of optical and ultrasound imaging, PAI probes SLNs non-invasively with methylene blue (MB) in both live animals and breast cancer patients. However, these PAI systems have limitations for widespread use in clinics and commercial marketplaces because the lasers used by the PAI systems, e.g., tunable liquid dye laser systems and optical parametric oscillator (OPO) lasers, are bulky in size, not economical, and use risky flammable and toxic liquid dyes. To overcome these limitations, we are proposing a novel dual-modal photoacoustic and ultrasound imaging system based on a solid-state dye laser (SD-PAUSI), which is compact, convenient, and carries far less risk of flammability and toxicity. Using a solid-state dye handpiece that generates 650-nm wavelength, we successfully imaged the MB tube positioned deeply (~3.9 cm) in chicken breast tissue. The SLNs were also photoacoustically detected in the in vivo rats beneath a 2.2-cm-thick layer of chicken breast, which is deeper than the typical depth of SLNs in humans (1.2 ± 0.5 cm). Furthermore, we showed the multispectral capability of the PAI by switching the dye handpiece, in which the MB-dyed SLN was selectively highlighted from the surrounding vasculature. These results demonstrated the great potential of the SD-PAUSI as an easy but effective modality for SLN detection.