This PDF file contains the front matter associated with SPIE Proceedings Volume 11968, including the Title Page, Copyright information, and Table of Contents.

Deep Ultraviolet (UV) Microscopy enables high-resolution, quantitative, and label-free imaging of biomolecules. Recently, we have shown that UV microscopy can be used as a tool for simple and fast hematology analysis by providing diagnostically relevant information on morphological and cytogenic properties of various blood cells. We have demonstrated the ability to classify and segment red blood cells, white blood cell subtypes, and platelets via deep learning frameworks and have applied this technique for diagnosis of blood disorders. In this work, we present a compact, low-cost deep-UV microscope capable of performing a rapid complete blood count (CBC). CBCs, one of the most commonly performed medical tests in the United States, provide critical counts of blood components used to monitor and diagnose blood disorders. This device can serve as a point-of-care alternative to modern hematology analyzers by leveraging endogenous biomolecular contrast from UV light to perform label-free hematology analysis. Here we discuss our approach of using simple, low-cost optics and hardware to enable fast and accurate imaging of blood samples. We demonstrate the capability of this system to scan and capture images of whole blood on blood smears and in custom microfluidic devices. We also show that these images can be used to segment, classify, and colorize blood cell subtypes. Lastly, we evaluate the efficacy of our stage translation system by assessing its positioning and translation accuracy.

Neutropenia is a blood disorder characterized by an abnormally low number of neutrophils in the bloodstream. This condition signifies an increased risk of infections, and thus can lead to life-threatening medical emergencies in severe cases. Therefore, it is critical to routinely monitor neutrophil counts in cancer patients. However, the current clinical standard-of-care for blood cell enumeration to assess neutropenia relies on complete blood count (CBC) which requires expensive and complex equipment, multiple reagents, and cumbersome procedures, impeding easy and timely access to critical hematological information. Here, we demonstrate the application of a microfluidic device which, along with deep-ultraviolet microscopy, enables stain-free and fixative-free hematological assessment of neutropenia. We demonstrate the capabilities of our approach in detection and staging of neutropenia by imaging samples obtained from healthy donors as well as moderate and severe neutropenia patients while verifying the results against CBC findings. This work has significant implications towards the development of a low-cost, and easy-to-use point-of-care device for tracking neutrophil counts.

The increasing performance and ubiquity of mobile phone cameras has led to several emerging opportunities for their use in global health and point-of-care diagnostics. High-resolution, low-cost microscopy can be achieved by pairing the cell phone lens with a second, identical lens in a reversed orientation, allowing 1x magnification over a large field of view. In previous work, we showed that reverse lens mobile phone capillaroscopy can visualize optical absorption gaps (OAGs) in nailfold capillaries. The frequency of these OAGs is known to be inversely correlated with degree of neutropenia. To extend this concept and enable the direct visualization of both red and white blood cells for more complete blood analysis, there is a need for improved resolution and phase contrast. Here, we present a design for a reverse lens mobile phone capillaroscope that pairs two different cell phone lenses to increase magnification for enhanced visualization. From an iPhone 12 Pro, the telephoto and wide cameras are combined with reversed wide and ultrawide lenses. The lens pairs provide magnification up to 4.02x and resolution up to approximately 1.49 μm, whereas the previous design only yielded a resolution of 3.75 μm. We use this system to image human blood in a microfluidic capillary phantom.

Today, approximately 5 million Americans are living with Congestive Heart Failure (CHF), and this burden is higher for African American communities, even for control groups. Implantable devices to measure pulmonary artery pressure are sometimes indicated as a surrogate measure for fluid retention in the lungs caused by worsening heart failure but are often inaccessible to underserved communities due to the prohibitive costs of the device and surgical procedure. Thus, we are implementing a sensitive immunoassay on a low-cost paper fluidic platform, to enable the frequent and easy measurements of B-type Natriuretic Peptide (BNP), an important biomarker secreted by cardiomyocytes in response to the increasing ventricular stretch and cardiac volume. BNP concentrations are often used to classify CHF into 4 levels of severity on the New York Heart Association (NYHA) scale. The paper fluidic cartridge is composed of thin, economical cotton, glass fiber and nitrocellulose membranes, that are modified to improve the flow of the sample volume. We incorporate a sandwich assay using surface-enhanced Raman scattering (SERS)-active gold nanoparticles for signal transduction, a BNP-specific aptamer for detection as well as stabilization of the nanoparticle conjugate, and a monoclonal antibody specific to BNP for the recognition element, onto this cartridge. By using a handheld Raman reader with a 638 nm excitation laser, we retrieve SERRS spectra for the malachite green isothiocyanate dye which corresponds to BNP capture ranging from 0.3 ng/mL (Stage II) to 1 ng/mL (Stage IV). We also show the visual, colorimetric detection of these concentrations using the RGB pixels from the test line, demonstrating the potential for a multi-modal approach for this diagnostic test.

A 3D printed microarray device towards COVID 19 (SARS-COV-2) detection with a limit-of-detection of <167 nM was demonstrated. An array of 1,166 microwells, 116 x 116 μm in size, were 3D printed and synthetic targets and probes specific to COVID-19 spike-proteins were detected to demonstrate a device towards point-of-care COVID-19 detection.

Considering the difficulty of measuring neurotransmitters in the field of biomedical research, a portable autonomous sensing and analysis system of neurotransmitters is needed. This type of device would improve the diagnostics of neurodegenerative diseases such as Alzeimer, Parkinson, Huntington diseases. Thus, in this work, we present a synthesis research paper to describe our device capable of measuring neurotransmitters in a liquid sample using functionalized ultrastable gold nanoparticles. It uses a colorimetric sensor to measure neurotransmitter indirectly. Indeed, using the colorimetric sensing approach, the plasmonic resonance band of nanoparticles shifts when they interact with neurotransmitters. The functionalization of the nanoparticles with dopamine-specific aptamer increases the response and selectivity towards the neurotransmitter of interest. Also, using ultrastable gold nanoparticles5 provides the potential to expose them to harsh conditions without agglomeration. Those harsh conditions includes the presence of salts that would otherwise compromise the efficiency of the sensing as well as conditions that are used to wash and clean the solutions (freeze drying, heating, ultracentrifugation and autoclaving). By being able to resist to those types of conditions, it gives the potential to recycle the nanoparticles to be reused for several sensing cycles. This sensing system uses a grism-based spectrometer design for the colorimetric analysis of neurotransmitters covering a bandwidth of 420 to 620 nm. Moreover, the system includes a microfluidic module for the manipulation of samples as well as an electronic module for data acquisition and analysis. Altogether, the system showed that the absorption spectrum of a nanoparticles sample with a resolution of 0.7 nm can be extracted autonomously using this system.

Cardiovascular disease is the leading cause of death in the United States. Thus, much work is being done to develop monitoring technologies to lessen its morbidity and mortality. A common cardiovascular sensing modality is photoplethysmography (PPG), which relates local blood volume to changes in the intensity of light reaching a photodetector after traveling through tissue. Sufficient PPG signal quality from individuals with certain physiologies/anatomies can be difficult to obtain: one such example is the absorbing effect of melanin, causing poor PPG signal from individuals with a dark skin tone. Using optical phantoms, in vitro testing systems can enable device developers to quickly explore device performance under different conditions to help ensure strong performance. Here, we propose a phantom testing system for the in vitro evaluation of PPG. A pump system flows blood phantom through a 3-layer polydimethylsiloxane (PDMS) tissue phantom (mimicking epidermis, dermis, subcutis) of the volar wrist with an inset vessel representing the radial artery. The pump changes pressure to represent pressure throughout the cardiac cycle, and a PPG sensor (660nm) is placed on the tissue phantom. The effect of skin tone is analyzed by using epidermal phantoms with different optical properties representing Fitzpatrick Skin Tone I (3% volume fraction melanosome) and Fitzpatrick Skin Tone III (15% volume fraction melanosome). It was found that the PPG sensor was able to successfully and accurately register the synthetic PPG waveform, and the PPG AC/DC ratio decreased 17.7% when comparing the 3% volume fraction melanosome phantom to the 15% volume fraction melanosome phantom.

Approximately 12 million people in the United States are affected by peripheral artery disease (PAD), characterized by an accumulation of plaque in the arteries of the lower extremities. In advanced stages, treating physicians often recommend a surgical intervention to improve blood flow to the feet. However, about 50% of patients require a second intervention within 12 months. Here we report on the potential of dynamic optical imaging (DOI) to predict the long-term outcome of such surgery. Our DOI system consists of four detection patches, each configured with two SI-detectors and four laser diodes at different wavelengths (678 nm, 780 nm, 808 nm and 850 nm). These patches are placed on four different angiosomes of the foot to record the dynamical responses to inflations and deflations of a thigh cuff. Inflating a cuff causes blood to accumulate in the foot, while deflating the cuff reduces the amount of blood. DOI measurements can be characterized by a response time to cuff inflation (rise time), and a plateau time between cuff inflation and deflation. For this study 16 patients with no previous history of interventions were enrolled, and DOI data was collected before and after the intervention. 4 of the 16 patients needed a second intervention within 6 months. We found a strong correlation between the changes in pre-and post-intervention rise time and the 6 months treatment outcome. A ROC analysis showed that it was possible to categorize outcomes correctly with an AUC (Area Under the Curve) of about 83%, and corresponding specificity of 100% and sensitivity of 75%.

Ulcers are a common occurrence in diabetic patients with peripheral arterial disease (PAD). Early prognosis of ulcer healing can help patients avoid prolonged pain and future amputation by alerting physicians to intervention efficacy. However, monitoring of ulcers and predicting intervention success remains a challenge. We have developed a so-called vascular optical tomography imaging system (VOTIS) to address this problem. The system consists of patches with infrared sources and silicon photodiodes. The patches are placed on areas of interest in the lower extremities and light attenuation data is obtained at multiple frames per second. During data acquisition, a thigh cuff is inflated and deflated to affect blood flow to the lower extremities, resulting in dynamic changes of the recorded signals. Features such as maximum change in total absorption, response time to cuff inflation, and plateau time (PT) between cuff inflation and deflation can be extracted. Here we report on a pilot study of 10 PAD patients (70% diabetic) with ulcers, who had a surgical intervention to improve blood flow. VOTIS measurements were obtained immediately after the intervention, and again three weeks later. Prognosis was determined from EHR and classified as improvement (N=7) - when an ulcer reduces in size - or no improvement (N=3). In an ROC analysis, the VOTIS-derived biomarker PT demonstrated high classification potential (Sn=86%, Sp=100%, AUC=0.95).

Obesity is a widespread chronic illness which affects over 40% of the US adult population and its world-wide prevalence has increased over the years impacting both low and high-income countries. Obesity has been linked to higher risk of non-communicable diseases such as cardiovascular disease, type-2 diabetes, dyslipidemia, hypertension, among others. Currently the mostly prescribed regimes to combat chronic illness associated with obesity are efforts to change diet, behavior, and physical activity. Wearable devices have the potential of helping users reduce their obesity levels as these devices can easily acquire and communicate biometric data with users and clinicians. However, these technologies depend on optical sensors that are sensitive to molecular skin composition. We hypothesize that individuals with high BMI levels will present changes in skin optical properties when compared to their non-obese counterparts. Our objective is to capture skin optical properties at the wrist among a diverse cohort using a commercial optical system for research use. To meet an appropriate power, the human study, composed of males and females, is conducted with 100 adult participants. Statistical methods, including linear regression and t-tests, are used to determine interactions between measured data and participant demographics. We believe these results can improve design of optical wearables for the obese.

The prevalence of heart failure (HF) has increased worldwide. Excessive fluid retention often causes leg edema in patients with HF, resulting in disease progression and readmissions. It is important that the severity of leg edema is regularly assessed in patients with HF. Although edema is assessed by indentation depth and leg circumference, these data may vary depending on the measurement procedure. Therefore, these methods are currently not accurate enough to evaluate edema. Diffuse reflectance spectroscopy (DRS) can detect conditions such as subcutaneous edema. Some studies have evaluated edema using DRS, but those studies have not been considered detailed parameters and where measurements should be taken. The objective of this study was to optimize DRS in evaluating leg edema. First, we investigated the ideal location for evaluating leg edema by characterizing the subcutaneous structures in various regions using ultrasound imaging. The medial part of the tibia was found to be appropriate for DRS measurement due to its simple, layered structure. Second, optical penetration depth was examined with different source-detector (SD) distances at wavelengths near the absorption peak of water. We found an appropriate SD distance was 10 mm, for measurement of water content in subcutaneous fat. Furthermore, a DRS system optimized using our findings was able to obtain good correlation between water content and absorbance in a leg edema phantom. These findings suggest that leg edema can be evaluated quantitatively in a DRS system. We anticipate that this system will aid management of fluid retention in patients with HF.

In this paper, we report the results of accuracy verification of a measurement method for capturing pulse waves from the sole of rodents using an RGB camera in a non-contact, non-invasive manner. In order to acquire biometric data such as pulse waves from animals, a non-invasive method is required to minimize the impact on the animal. We experimented with verifying the accuracy of pulse waves using an RGB camera synchronized with the electrocardiogram (ECG). As a result, our proposed method of detecting pulse waves from the sole was observed to measure pulse rate with similar accuracy to an ECG. The deviation of the heartbeat interval was somewhat larger for the proposed method than for the ECG; the maximum absorption peak of the Green signal showed the same pattern in the extremities, indicating that the deviation of pulse wave propagation was larger than 1/250 s. The deviation between the R-wave peak of the ECG and the maximum absorption peak of the sole was 0.1 s.

In the paper we demonstrate the applicability of optical coherence tomography angiography (OCTA) and optical coherence tomography lymphangiography (OCTL) to investigate changes in intramural blood and lymph flow of the small intestine in an experimental model of spinal trauma with sympathetic denervation of the gut. Resection of sympathetic ganglia was performed in rabbits using the retroperitoneal approach. Lymph and blood circulation in the small intestine wall was evaluated before and after the spinal trauma. For OCTL images the signal attenuation coefficient was quantitatively analyzed, and the areas that did not scatter or absorb light in the infrared range were assigned to the lymph. It was shown that the changes in blood microcirulation are significant, hovewer the significance of changes in lymhatic vessels density is hard to estimate due to high variations of data.