In this novel multimodal wide-field Raman microscope, spectra are obtained by the time-domain Fourier-transform method. The wide-field approach enables faster collection of Raman maps, while the time-domain method disentangles fluorescence and Raman signals. This is obtained by choosing a proper sampling of the interferogram, thanks to the use of an ultrastable common-path birefringent interferometer. Validation of the system is performed on plastic microbeads; multimodality is demonstrated by fluorescence and Raman maps of a few-layers transition metal dichalcogenide sample.

Diffuse in-vivo Flow Cytometry (DiFC) is a fluorescence sensing method to detect labeled circulating cells in-vivo non-invasively. The Dual-Ratio (DR) is an optical measurement method that aims to suppress most noise and enhance SNR in deep tissue regions. We investigate DR applied to Near-InfraRed (NIR) DiFC to improve circulating cells’ maximum detectable depth and SNR. Results indicate that two critical conditions control the success of DR DiFC. First, the fraction of noise that DR methods cannot cancel (i.e., non-multiplicative factors) cannot dominate. Second, DR DiFC has an advantage regarding SNR if the spatial distribution of tissue autofluorescence contributors is surface-weighted.

We have developed an advanced design for a dual-wavelength laser source used in Coherent Anti-Stokes Raman scattering (CARS) microscopy and Stimulated Raman Spectroscopy (SRS) addressing a wider frequency range for bio-imaging, spanning from <630cm^-1 to 2250cm^-1, while maintaining a fast tuning time of a few seconds across the entire range. Furthermore, we have achieved improved tunability of the Stokes and pump power, allowing for versatile applications. The system supports repetition rates of up to 10MHz, and the spectral width of the signals is narrow (<15cm^-1), enabling a wide range of potential uses.

Obstetric risks, associated with pre-eclampsia, such as maternal age and pre-existing conditions are on the rise, along with the risk of ectopic calcification and placental vascular dysfunction. We investigated Slc20a2 mice models through non-invasive commercialized and synergistic ultrasound and photoacoustic imaging, which provide dual-wavelength images and radio frequency data. The increased ectopic placental vascular calcification model exhibits reduced fetal growth and decreased postnatal bone mineral density. Our experiments established a significant difference in both placental function and structural differences between normal and diseased placentas through the provided oxygen saturation and quantitative ultrasound spectral parameters.

Bladder cancer (BC) in US men is costly and common; its high cost largely from its high recurrence rate (>50%), which necessitates frequent surveillance. We aim to change the paradigm around how BC surveillance is performed by validating new tools with high sensitivity and specificity for carcinoma in situ. In this talk, I discuss our innovative solutions to improve mapping the bladder for longitudinal tracking of suspicious lesions and to create miniature tools for optical detection based on machine learning, computer vision and optical coherence tomography.

Our prior work has established that SFDI metrics can be used to assess skin involvement in scleroderma. To ease clinical translation of SFDI for SSc disease assessment, a preliminary design for a handheld SFDI system optimized for measurement of sclerodermatous skin is proposed. An LED is used as an illumination source, light is modulated using a printed transparency, and Rd is extracted using single snapshot demodulation methods. Additionally, the imager can measure scattering orientation using a rotating pattern. The performance of the imager was assessed using phantoms, and its inter- and intra-observer reliabilities were assessed.

We demonstrate an entirely handheld frequency-domain near-infrared spectroscopy imager capable of displaying 2D images in real-time. The system provides high flexibility using a multi-wavelength (6 sources, 690 - 980nm), multi-frequency (50-400MHz), multi-channel (3 detectors) approach that addresses many of the limitations of prior fdNIRS systems including system size, speed, and ease of use.

Exploiting the optical absorption contrast of blood hemoglobin, photoacoustic microscopy (PAM) is an emerging technology for label-free imaging of the microvasculature, which plays an essential role in supplying biological tissue with oxygen and sustaining metabolic activity in vivo. The multi-parametric PAM developed in Dr. Hu’s lab enables comprehensive and quantitative characterization of microvascular structure, function, and tissue oxygen metabolism at the microscopic level. In this talk, Dr. Hu will present their latest progress on the development of PAM and the integration of PAM with other intravital light microscopy techniques for studying brain function and energy metabolism across spatiotemporal scales.

We aim to highlight the potential of label-free, TPEF metabolic imaging to gain unique insights in the development of Alzheimer’s disease (AD). Using an engineered brain tissue model infected with HSV-1 to induce AD phenotypes, we focus on dynamic changes associated with metabolic function, as reported by both the redox ratio and mitochondrial clustering, and the development of Aβ+ fibrillar plaque like formations (PLFs).

We developed and evaluated a low-cost, miniaturized, and user-friendly speckle contrast diffuse correlation tomography (scDCT) device for noncontact, fast, high-density, and depth-sensitive imaging of CBF distribution in the brain. The new low-cost portable scDCT device was evaluated against an established large scDCT system using head-simulating phantoms with known optical properties and the mouse with transient ligations of common carotid arteries. Results taken from the two scDCT systems were highly consistent. The low-cost miniaturized scDCT has the potential to be commercialized as an affordable, portable, and ergonomic brain monitoring tool for neuroscience research in numerous academic and industrial laboratories.

Fluorescence imaging has been widely used during tumor surgery which allows the surgeon to recognize the tumor’s location and edges better. However, traditional fluorescence-guided surgery (FGS) usually uses steady-state fluorescence images which only could provide a flat view of the target but lack depth information. Here we use the Time-Of-Flight (TOF) method to measure the distance between the sensor and the target, which would allow us to distinguish objects surrounded by background fluorescence. By comparing the temporal profiles of different fluorescence embeddings, we could colormap the fluorescence images and show differences in depths. Moreover, we proposed a deep learning model that combines CNN and time-based model (LSTM) to capture more precise depth maps and 3D information. We trained and validated this new network using the Monte-Carlo-based simulation datasets.

Mesoscopic oblique plane microscopy (Meso-OPM) leverages the key advantages of traditional light sheet microscopy yet has the advantage of high-speed dynamic imaging. Here we present a new Meso-OPM system that maintains a large FOV and cellular resolution, while achieving >5Hz volumetric rate for dynamic calcium imaging in biological specimens.

Optical imaging in musculoskeletal systems can provide dynamic cellular-resolution analysis of biological tissues and regenerative processes. Here, we advance multiphoton imaging and analysis techniques to explore therapeutic cell homing in the bone, mitochondrial dynamics during regeneration in muscle and bone, and collagen organization in metabolic bone disorders. We develop aberration correction approaches to recover high-resolution imaging of cell dynamics deep in the bone marrow and in muscle. We leverage our imaging techniques to explore single mitochondrial dynamics in skeletal muscle, and the disruptions in mitochondrial order that occur after volumetric muscle loss. Finally, we have developed second harmonic generation imaging using polarized light for analysis of bone collagen assembly into lamella sheet structures and have investigated collagen organization in metabolic bone disorders. Our findings could provide insight into dynamic processes driving musculoskeletal homeostasis and fragility disorders.

Diffuse optical spectroscopies are non-invasive, light-based tools that enable real-time bedside monitoring of microvascular hemodynamics in the brain. This talk will highlight recent work in two high-risk patient populations at high risk of stroke (subarachnoid hemorrhage and sickle cell disease) to explore how these tools work and how they can be used to identify biomarkers of stroke.

Here, we explore the potential benefits of extracting hemoglobin oxygenation metrics using multispectral imaging (MSI) in nailfold capillaroscopy for systemic sclerosis (SSc) patients. We used a nine-band multispectral camera to capture images of the nail bed from SSc patients (n=10) and healthy controls (n=12). Spectral analysis and machine learning classification were employed to examine systematic changes between healthy controls and SSc patients. The results demonstrate differences in spectra and promising accuracy in classification, with further work needed to extract oxygenation values and improve signal-to-noise ratio. MSI shows potential for improving sensitivity of nailfold capillaroscopy and detection of changes in early disease.

We present here a new technique called Frequency Domain Shortwave Infrared Spectroscopy (FD-SWIRS), which provides absolute broadband optical property extractions as well as tissue water and lipids concentrations using shortwave infrared light. Measurements from a custom digital FD system at 730, 852, 940, and 980 nm were combined with broadband continuous wave (CW) measurements (900 - 1310 nm). FD and CW measurements were integrated using model-based analysis to provide broadband absolute absorption and reduced scattering spectra. Intralipid and heavy water titrations, drift, SNR, a porcine desiccation experiment, and other key experiments were conducted to characterize the system.

My talk will focus on the application of single molecule time-resolved fluorescence spectroscopy as a tool to explore in real time the protein-nucleic acid interactions and dynamic structural rearrangements that drive biological pathways. We are currently studying the detailed mechanisms SARS-CoV-2 viral RNA processing, ribosome assembly, and DNA mismatch repair. I will present recent results from pulsed interleaved excitation fluorescence resonance energy transfer (PIE-FRET) and fluorescence correlation spectroscopy (FCS) experiments. We aim to completely characterize the impact of mutations linked to disease on the molecular function of enzymes to understand how complex diseases develop at the molecular level and to identify new therapeutic targets.

We investigated the impact of laser coherence length on reconstructed flow contrast images with our innovative speckle contrast diffuse correlation tomography (scDCT) device. We tested three lasers with varied coherence lengths: >10 meters, ~3.3 millimeters, and ~390 micrometers. Lasers with coherence lengths larger than millimeters yielded good-quality flow images with higher signal-to-noise ratios (SNR) and less image distortion. We concluded that scDCT measurements do not require excessively long coherence lasers with high costs.

We present a polarized light-sheet microscopy and tomography system, PLμTo, for versatile multi-scale and multi-modal volumetric optical imaging. The system can utilize fluorescence and elastic scattering contrast for visualization of biochemical and structural information. PLμTo is compatible with traditional slide and well-plate sample mounting, as well as microfluidics for high-throughput volumetric imaging flow cytometry of mesenchymal stem cells cultured on spherical microcarriers in a bioreactor culture. Additionally, the system is capable of rapidly screening millimeter-sized cleared tissues with cellular level resolution in a few minutes. This system can be utilized to study biological processes at varying spatial and temporal scales.

Conventional pathology workflows rely on two-dimensional, slide-based analysis of thin tissue sections. This approach comes with several key limitations including limited sampling, lack of 3D structural information, and destruction of valuable clinical specimens. There is growing interest in nondestructive 3D pathology to address these shortcomings. Existing work has mainly focused on small-scale proof-of-concept studies, due in part to the difficulty of producing consistent, high-quality 3D pathology datasets across hundreds to thousands of specimens. To facilitate large-scale clinical studies, we present an end-to-end workflow for 3D pathology, with an emphasis on data consistency and quality control.