This PDF file contains the front matter associated with SPIE Proceedings Volume 11230 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Spatial Frequency Domain Imaging (SFDI) is a quantitative imaging method that measures optical properties of tissue. We present the design of a compact spectral imager to perform SFDI in low resource settings, which exploits a low-cost color CMOS camera and mini-projector. These devices are usually limited to three broad spectral bands (RGB). We have developed a novel method to extrapolate two additional wavelengths without hardware modifications, improving the spectral resolution of the device, allowing to account for additional sources of skin pigmentation. Our device performance was evaluated on tissue-simulating phantoms. In-vivo measurements were compared to a commercial probe-based system (EPOS).

Novel tools for malaria diagnosis, particularly rapid diagnostic tests (RDT’s), have provided alternatives to laboratory based microscopic disease confirmation. While RDT’s provide a disposable, low-cost option for parasite detection and some level of speciation, they fail to quantify parasitemia, which is useful in monitoring morbidity and identifying candidates for intensive treatment regimens. A low-cost microscope designed to gather quantitative parasitemia data from blood smears generated in microfluidic cartridges is presented. The system employs bi-modal imaging and uses components selected to optimize cost savings, system robustness, and optical performance. Bimodality is achieved by capturing two subsequent images for each field-of-view, with transmission-mode images providing cell counts and fluorescence-mode images providing biomarker localization data. A monochromatic LED for transmission illumination is employed with center wavelength aligned to the fluorophore label (acridine orange) emission peak near 520nm. Ray-trace models have been used to characterize performance while imaging in microfluidic cartridges with varying wall thicknesses. Results indicate that the necessary sub-micron resolution can be achieved using polymeric aspheres as critical optical components. System design and characterization results are presented from Zemax raytrace models, and imaging data from the prototype system are presented with correlations to modeled configurations. By optimizing the microscopy system to address a highly specific diagnostic gap, its complexity and cost can be reduced toward feasibility in the developing world while preserving utility as a potentially valuable tool to augment current malaria diagnosis and monitoring technologies.

Accurate self-testing of coagulation status by patients receiving anticoagulant therapy can reducing the burdensome need for frequent and expensive laboratory testing. We have developed a new smartphone-adaptable optical module that provides multi-functional assessment of blood coagulation status with a drop of blood via a finger-stick draw. The spatial speckle contrast imaged on a smartphone camera through our optical module evolves in time as blood coagulates. Studies using blood samples tested at hematology laboratory in hospital show strong correlation with our speckle contrast results for activated partial thromboplastin time (aPTT) and prothrombin time (PT).

Mobile phone microscopy has the ability to transform clinical and public health care in low-resource settings. This session will explore innovative approaches to mobile phone microscopy, and then discuss how mobile microscopy can be integrated into low-resource settings. We will examine creative microscopy solutions to tackle diagnostic challenges, and evaluate current pitfalls to implementation and scale of mobile phone microscopy. The session will also focus on field implementation of microscopes, and how to best engineer and design devices for use in low-resource settings.

Monitoring serum phosphate level is critical for patients with kidney disease and those undergoing dialysis. We report a POC serum phosphate measurement device, by integrating a disposable paper-based microfluidic chip with a smartphone-based measurement system. The inexpensive microfluidic chip collects a droplet of blood from the patient and isolates the serum, which then reacts with a malachite green reagent, resulting in a colorimetric change, measured using a smartphone-based device. This POC instrument was tested on clinical samples obtained from patients undergoing dialysis, and we observed a strong statistical correlation between our results and the tests performed in a clinical laboratory.

We report the development of field-portable multi-modal chip-based fluorescence, bright field and quantitative phase microscopy using smartphone detecting system. Fluorescence microscopy provide molecular information of the specimen with excellent specificity, while phase microscopy provides quantitative information of the specimen. Quantifying the optical phase shifts associated with biological structures gives access to information about morphology and dynamics at the nanometer scale. Here, we propose an integrated waveguide chip-based total internal reflection fluorescence (TIRF) microscopy and quantitative phase microscopy (QPM). We have developed microLED with cylindrical beam profile to couple excitation light into the edges of glass slide easily and efficiently. The evanescent field present on top of a waveguide surface is used to excite the fluorescence and a mobile phone microscope is used to collect the signal. Waveguide chip-based TIRF microscopy benefits from decoupling of illumination and collection light path, large field of view imaging and pre-aligned configuration for multi-color TIRF imaging. Light for bright field imaging and QPM integrated in the transmission mode. A microscope objective is used for collecting the fluorescence excited by evanescent field and transmitted light for bright field and quantitative phase microscopy (QPM). A compact and common path interferometer is used for QPM. The entire device is fabricated using three-D printer and integrated into one, which is compact and field portable. Images are recorded using a smart phone. Experimental results of onion epithelial cells, polystyrene microspheres and normal breast tissue are presented. The cost of entire system is very less.

We demonstrate a low-cost and rapid paper-based vertical flow assay (VFA) for quantification of C-Reactive Protein (CRP). We use deep learning-based analysis of this VFA and its multiplexed sensing channels to achieve accurate quantification, as well as to overcome fabrication and operational variations along with limitations borne out of the hook effect, validating our results with clinical samples. This computational point-of-care test could be used for stratification of patients into cardiovascular disease risk assessment groups following standard clinical cut-offs. It can also broadly serve as a computational sensing platform for future point-of-care sensing and diagnostic applications.

We report a highly-sensitive, high-throughput, and cost-effective bacteria identification system which continuously captures and reconstructs holographic images of an agar-plate and analyzes the time-lapsed images with deep learning models for early detection of colonies. The performance of our system was confirmed by detection and classification of Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae in water samples. We detected 90% of the bacterial colonies and their growth within 7-10h (>95% within 12h) with ~100% precision, and correctly identified the corresponding species within 7.6-12h with 80% accuracy, and achieved time savings of >12h as compared to the gold-standard EPA-approved methods.

We introduce a cost-effective imaging method using droplets of consumer-grade cooking oil and a cell phone camera. While cooking oil droplets are not specifically designed for imaging, we found that, similar to immersion oil, they were more resistant to evaporation than water, thereby enabling long-term imaging. We harnessed their close refractive index to immersion oil and demonstrated their use as lenses for cell phone microscopy. Our new method enables stable droplet-based optical imaging primarily using household materials without specialized setups or manufacturing processes.

Protein-based therapeutics have been developed to treat a range of conditions and assays use immobilized capture proteins for the detection of diseases. A challenge in the development of protein-based products is maintaining the protein in the folded state during processing and storage. The most common method of stabilizing proteins for storage is lyophilization. However, the freeze-drying process remains expensive and many proteins that are lyophilized must be refrigerated or frozen to maintain functionality. Cold storage strategies can be challenging for the transportation of protein-based products and can be difficult or impossible in low resource settings. Recent research has demonstrated that anhydrous, or dry state, preservation in a trehalose amorphous solid matrix offers an alternative to freeze drying for the preservation of biologics. We have previously described a new processing technique, light assisted drying (LAD), to create trehalose preservation matrices. LAD uses illumination by near-infrared laser light to selectively heat water and speeds dehydration of small volume (40 μL) samples. Low end moisture contents (EMC’s) are necessary for storage at supra-zero temperatures and this low water content must be uniform to insure successful long-term storage of embedded biologics. Our previous work has demonstrated the ability of LAD to reach EMCs necessary for storage at elevated temperatures. In this work, Raman spectroscopy is used to assess the trehalose distribution and water content across LAD processed samples. Results indicate that the water content of LAD process samples is uniform. LAD is a promising technique for processing biologics in preparation for anhydrous storage.

We propose a self-evaluation of visual field using free-focus retinal scanning laser display technology based on Maxwellian-viewing optics. The developed device was the combination of commercially available smartphone with built-in laser pico-projector and newly developed additional optics to realize Maxwellian-view and eye-safety. Movie with flying and fixed gazing spot was displayed on the subject’s retina for evaluation. The non-recognition areas were found by the self-evaluation not only at the Marriott blind spot but at other area corresponding to the abnormal visual field in the Amsler chart test related to the inflated upstream blood vessel due to the retinal vein occlusion.

The use of microfluidic channels as an imaging platform within microscopy systems provides the potential for a low-cost point-of-care system. Glass is traditionally used as a binding substrate for polydimethylsiloxane (PDMS) channels because of its optical favorability, however its cost and mechanical properties make it less than ideal. Glass’ range of thicknesses (174 microns to 1mm) can create the issues of increased fragility at the lower thicknesses and induced optical aberrations at the higher thicknesses, respectively. Therefore, a thin optically transparent plastic becomes a favorable low-cost substitute for a binding substrate. Plastics such as polycarbonate, polyester, and polyvinylchloride were studied as potential substitutes based on a combination of their material and optical characteristics. Studied material characteristics include the thermal expansion of the material along with the bond strength between the plastic and PDMS. Resolution limitations caused by the plastic materials were measured using a 1951 U.S. Air Force target and portable microscopy system. Preliminary data suggests that when trying to resolve features as small as 0.78 microns, 0.254mm thick polycarbonate performed better than 1mm thick glass. To determine the optical limitations of the plastic substrate PDMS microchannel as an imaging platform, whole blood infected with Plasmodium falciparum was viewed through the channel within the same portable system, and individual blood cells and malaria parasites were attempted to be resolved. Results suggest the use of a thin-film plastic as the substrate for microfluidic channels provides a robust low-cost imaging platform.

The use of wearable devices is changing the way patients manage many chronic health conditions, such as diabetes and cardiovascular disease, outside the clinic. The ability of wearable to provide continuous monitoring makes them particularly suitable for the management of these chronic disorders which are disproportionately present in minorities. Compared to Caucasians, African American are 30% more likely to die of cardiovascular diseases, while Hispanic and Latino are 65% more likely to be diabetic. These groups have also significant higher rate of obesity. In this talk we will introduce some of our work aimed at the development of optical wearable devices targeting chronic diseases. We will show, through Monte Carlo modeling, how common optical wearable devices do not address the need of all users and are particularly limited in dealing with highly pigmented skin tones as well as large adipose layers. Strategies to overcome these limitations will be presented.

We demonstrate a contact-lens (CL) based mobile sensing system which can be used to measure protein levels in human tear. By using a cost-effective mobile-phone-based well-plate reader and a fluorescent assay, we quantify lysozyme nonspecifically bound to CLs. We monitored the lysozyme levels of 9 healthy volunteers to establish individual baselines, and then compared these measurements to participants who had been diagnosed with Dry Eye Disease (N=6), observing a statistically significant difference in their means. Due to its non-invasive and simple operation, this method could be used for tear-based sensing and health monitoring applications in point-of-care settings and at home.

We demonstrate an automatic, high-throughput and high-sensitivity particle aggregation-based sensor that uses wide-field, compact and cost-effective lens-less microscopy, powered by deep neural networks. In this method, the post-reaction assay is imaged by a snapshot hologram over a wide field-of-view (20mm²). Using a deep learning-based holographic reconstruction, all the particle clusters are simultaneously reconstructed in ~30s. Using this method, we demonstrated accurate and rapid readout of an immunoassay to detect herpes simplex virus, which affects >50% of the adults in US, and achieved a clinically-relevant detection limit (~ 5viruses/µL). This method can be broadly used to quantify other particle-aggregation based immunoassays.

We report a deep learning-based colorization framework for holographic microscopy, and demonstrate its efficacy by imaging histopathology slides (Masson’s trichrome-stained lung and H&E-stained prostate tissue). Using a generative adversarial network, this framework is trained to eliminate the missing-phase-related artifacts. To obtain accurate color information, the pathology slides were imaged under multiplexed illumination at three wavelengths, and the deep network learns to demultiplex and project the holographic images from the three color channels into the RGB color-space, achieving high color-fidelity. Our method dramatically simplifies the data acquisition and shortens the processing time, which is important for e.g., digital pathology in resource-limited-settings.

Early diagnosis of melanomas is the most effective means of improving melanoma prognosis. We can arm the non-expert screeners with artificial intelligence but most artificial intelligence methods are somewhat impractical in a clinical setting given the lack of transparency. To provide a quantitative and algorithmic approach to lesion diagnosis while maintaining transparency, and to supplement the clinician rather than replace them, our digital analysis provides visual features, or, “imaging biomarkers” that can both be used in machine learning and visualized too.

Oral cancer is one of the most common malignant tumors. There are 354,864 new cases and 177,384 death per year globally according to Globocan 2018 report. Most of the cases are in low- and middle-income countries that lack trained specialists and health services, of which India accounts for approximately one-third of the new cases and two-fifth deaths. Point-of-care oral screening tool to enable early diagnosis is urgently needed. We developed a dual-mode intraoral oral cancer screening platform and an automatic classification algorithm for oral dysplasia and malignancy images using deep learning.

For over 20 years, functional Near Infrared Spectroscopy (fNIRS) has helped shape research in neurocognitve development. Furthermore, it has provided means to explore markers of compromised development. It is now being applied to investigate socio-economic and environmental links in this process. The Brain Imaging for Global Health (BRIGHT) project is a longitudinal study that aims to provide brain function for age curves in high- and low-resource settings, with 62 enrolled families in the UK, and 223 in The Gambia. Behavioural, nutritional and growth information collected in the project may help explain differential responses within and between the groups.

Multiple reference optical coherence tomography (MR-OCT) is a time-domain interferometric imaging platform which promises to be realized as a low cost, compact imaging technology. The optical configuration of MR-OCT makes use of multiple reflections between a partial mirror and the axially scanning reference mirror to enhance the axial imaging depth compared to the otherwise shallow scanning range of the voice coil or piezo actuator. Since each reflection on the partial mirror causes an optical path delay, the focusing of each higher order of reflection is changing. That means the beam diameter, beam collimation and therefore the interference visibility are changing as well. This investigation focuses on how the spacing between the partial mirror and the scanning mirror affects the system’s sensitivity and SNR values. The potential to improve the sensitivity of higher orders of reflections related to deeper regions in a sample will be studied.

In a world with a growing need for rapid medical diagnosis, point-of-care devices based on optics have become an interesting solution. Moreover, the low cost, simplicity, and ease of use also become essential to be applied in a clinical environment. Nowadays, smartphones are an attractive, user-friendly option, but the rapid changes in the models, the variety of brands, and the risk of contamination of personal smartphones in a clinical situation make this choose not the best one. Single-board computers as Raspberry Pi can be an alternative for a low-cost imaging device that allows image acquisition, visualization, and processing. This study describes a portable system capable of acquiring and processing white light and fluorescence images, suitable for clinical purposes. The system consists of a single-board computer (Raspberry Pi 3B+, Raspberry Pi Foundation, UK) coupled to a digital camera and a touchscreen display. The portable device comprises six violet LEDs (emitting at 407 nm) to excite the tissue and a long-pass optical filter to acquire the fluorescence images; four white LEDs to obtain the white light one, besides a digital camera to perform the acquisition itself. The images are saved in the singleboard computer, where an algorithm written in Python (Python Foundation) calibrates the camera, acquires, and processes the acquired images, interacting with the user through touch with a GUI. Being a portable, easy to use, low-cost system, this device is convenient to be used in a clinical environment and allows a fast diagnosis and the possibility to be reproduced for widespread point-of-care use.

We describe a visible-light multi-spectral system for vascular oximetry studies that can be implemented in lowand middle-income countries, using a low-cost electronics and optical elements, for instance a Raspberry Pi, a Pi camera under a resolution of 5-megapixel, 2592x1944-pixel resolution, and four different light sources at 480nm, 532nm, 593nm and 610nm on a singular structured illumination area. It is designed to quantify the vascular oxygen saturation change of the rat dorsal spinal cord, which uses a Phyton custom application that synchronize all elements to execute the imaging process in one system, powered by a portable rechargeable 5V battery pack. Aimed for drug discovery, tracking disease progression and understanding of progressive and degenerative diseases. By replacing expensive and bulky imaging systems.