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Ophthalmic viscosurgical devices (OVDs) are essential medical tools for ophthalmic surgeons to use routinely in cataract surgery. OVD endotoxin contamination has been implicated in toxic anterior segment syndrome, a severe inflammatory condition after surgery. Current standard methods for endotoxin detection in medical devices rely on dwindling Horseshoe Crab resources for Limulus amoebocyte lysate assay or rabbit intracameral and intravitreal assays. Endotoxin recovery from OVDs poses particular challenge due to the nature and composition of the device. In the present proof-of-concept study, we demonstrate real-time detection capability of endotoxin by employing a noncontact and label-free fiber-optic Fourier transform infrared transmission spectroscopy based sensing method in the midinfrared spectral range of 1.6–12 μm. We performed testing on OVD samples spiked with a series of different concentrations of endotoxin. The study suggested that endotoxin contamination in OVD might be associated with fingerprint spectral peak shift in the wavenumber ranges of $\text{2925}- \text{2890}\,\text{cm}^{- 1}$ and $\text{1125}-\text{1100}\,\text{cm}^{- 1}$ , and the distance of shifting is dependent upon endotoxin concentration in OVD. FO-FTIR integrated with multivariate approaches such as hierarchical clustering and principal component analysis provides significant differentiation of OVD, endotoxin, and contaminated OVD at different concentrations.

Bacterial contamination on medical device surfaces is a critical public health concern. In order to detect bacteria on medical device surface, alternative methods for quantitative, accurate, easy-to-use, and real-time detection and identification of microorganism contamination are needed. We have recently presented a novel proof-of-concept platform for non-contact, label-free and real-time detection of surface contamination employing a fiber-optic Fourier transform infrared (FO-FTIR) spectroscopy sensing methodology in the mid-infrared (mid-IR) spectral range of 1.6–12 μm. In the present study, we demonstrate the detection capability and sensitivity of the integrated FO-FTIR approach using four species of commonly encountered bacteria: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pneumoniae. FO-FTIR combined with multivariate approaches such as hierarchical clustering and principal component analysis provided specific mid-IR spectral differentiation of the four microorganisms including when the sample contained mixtures of bacteria types. To assess the sensitivity of the FO-FTIR platform, bacteria samples were prepared at 109 colony forming unit (CFU)/μL and then serially diluted 1:10 eight times. The salient findings of this investigation showed that the integrated FO-FTIR based sensor can detect the presence of the bacteria at concentrations between 103 and 104 CFU/2 μL, producing unique bacteria signatures with high reproducibility. The advanced features of this sensing method in terms of sensitivity, specificity and repeatability employing non-contact, label-free, and real-time approaches, demonstrate its potential use as an alternative effective screening tool for routine monitoring of bacterial contaminated surfaces.

An advanced sensing methodology based on a noninvasive label-free fingerprint infrared spectroscopy approach for detecting and identifying intrinsic biomarkers related to the safety and efficacy of optical diagnostics and therapeutics technologies and devices is presented.

We demonstrate a novel integrated fiber-optic Fourier Transform Infrared (FO-FTIR) spectroscopy sensing approach for non-contact, rapid and chemical-free detection of pathogenic contamination on medical device surfaces. A proof-of-concept experimental sensing platform is validated through multivariable analytical studies.

Here we present detailed transmission measurements of ex-vivo lens capsule from 40,000 cm−1 to 800 cm−1. Time-dependent measurements were also performed to eliminate water absorption.

Optical methods have a long history in the field of medical diagnosis. The biomolecular specificity possible with optical methods has been particularly valuable in microscopy and histopathology while in vivo imaging of deep structures has traditionally been the domain of X-ray and MRI. The use of optical methods in deep tissue has been limited by multiple-scattering which blurs or distorts the optical signal. New stochastic methods which account for multiple scattering have been developed that are extending the usefulness of optical methods deep into tissue. In optical mammography, photons may travel through 10cm of tissue before arriving at the detector. We have developed a method for quantifying parameters of anomalous sites in breast tissue that may be used for functional characterization of tumors. In other work presented here, we are developing fluorescence based methods to detect and monitor tumor status. The immune response to a tumor is a target for fluorescently labeled specific antibodies. We have developed a method to localize the tumor site using CW fluorescence. Additionally, we have developed a method which uses time-resolved data and capitalizes on probe lifetime sensitivity to metabolic parameters such as pH and temperature to obtain functional information from the tumor site.

Our latest system for the imaging of temperature and other thermal properties of the skin provides not only precise temperature distribution of the skin but also high-speed measurement of emissivity and inertia distribution. The method enabled us to measure the emissivity and thermal inertia of the skin even when the temperature distribution of the inner surface of the hood was not uniform. Two-dimensional measurement with hood switching, and a single-hood measurement system were considered.

We present a novel approach for non-contact, rapid and chemical-free decontamination of medical device surfaces using near-infrared ultrashort (nano- to femtosecond) pulse lasers. A proof-of-principal experimental platform is validated through multivariable comparison studies.

An attempt was made to image the thermal inertia (defined as the square root of the product of thermal conductivity, specific heat and density) of the skin to observe the distribution of blood in the skin during post-occlusive reactive hyperaemia in normal healthy volunteers. The method was based on the ability to calculate thermal inertia by successive thermographic measurements of the skin after stepwise change in ambient radiation temperature surrounding the skin area. The stepwise change was achieved within 0.1 s through a single hood. Experimentation on the undisturbed volar forearm of normal subjects at the same site showed that the measurements thus achieved were reproducible. The thermal inertia values of forearm skin in normal subjects were scattered throughout the range 1.1 x 10(3) to 1.7 x 10(3) W s(1/2) m(-2) K(-1). Experiments on forearm skin subjected to arterial cuff occlusion indicated that thermal inertia can be detected at a low level of blood perfusion. A linear relationship was observed between thermal inertia and blood perfusion measured by laser Doppler imager before and during blood flow occlusion. During reactive hyperaemia, the thermal inertia image exhibited a non-uniform island-shaped pattern of distribution over the forearm, suggesting that, after release from occlusion, recovery of blood flow is non-uniform.

The designed polarization adapter is incorporated into a colposcope provides illumination with polarized light and capturing of orthogonally polarized images, using liquid crystal retarder and polarizer. Pearson correlation analysis is used to characterize subsurface structures.

A novel method for estimating lifetime of deeply embedded fluorophores, based on scaling relations for photon migration is presented. It is experimentally substantiated for targets embedded in turbid medium, using our lifetime fluorescence imaging system.

To enhance visibility of hidden anisotropic structures of biological tissues, geometry of sample illumination was optimized. Imaging of Pearson correlation coefficient of the degree of polarization was used to determine regions of statistical similarities.

Anisotropy of mouse and human skin is investigated in vivo using polarized videoreflectometry. An incident beam (linearly polarized, wavelength 650 nm) is focused at the sample surface. Two types of tissuelike media are used as controls to verify the technique: isotropic delrin and highly anisotropic demineralized bone with a priori knowledge of preferential orientation of collagen fibers. Equi-intensity profiles of light, backscattered from the sample, are fitted with ellipses that appear to follow the orientation of the collagen fibers. The ratio of the ellipse semiaxes is well correlated with the ratio of reduced scattering coefficients obtained from radial intensity distributions. Variation of equi-intensity profiles with distance from the incident beam is analyzed for different initial polarization states of the light and the relative orientation of polarization filters for incident and backscattered light. For the anisotropic media (demineralized bone and human and mouse skin), a qualitative difference between intensity distributions for cross- and co-polarized orientations of the polarization analyzer is observed up to a distance of 1.5 to 2.5 mm from the entry point. The polarized videoreflectometry of the skin may be a useful tool to assess skin fibrosis resulting from radiation treatment.

Equi-intensity contours of photometric patterns of backscattered focused linearly polarized light were fitted with ellipses. The orientation and ratio of semi-axes lengths revealed correlation with collagen fiber orientation. Optical anisotropy parameters were measured.

Inflammation of the oral epithelium has been shown to provide a promotional environment for evolving cancer cells. This has led to chemoprevention trials exploring the effectiveness of various anti-inflammatory drugs. These trials require quantitative assessment of epithelial inflammation which are traditionally provided by punch biopsy. To reduce patient discomfort and morbidity, we have developed a non-invasive alternative using diffuse reflectance spectroscopy. Though any optical system has the potential for probing near-surface structures, traditional methods of accounting for scattering of photons are generally invalid for typical epithelial thicknesses. We have developed a theory that is valid in this regime and our Monte Carlo simulations and phantom models of a two layered structure have validated our approach. We use a differential measure with accurate sensitivity to small changes in layer scattering coefficients. Preliminary results from this work are encouraging and further development is planned to enable quantification of epithelial thickness in vivo.

For individuals with cancer risk factors, reducing tissue inflammation may reduce the risk of developing cancer. This is the basis of several clinical trials evaluating potential chemoprevention drugs. These trials require quantitative assessments of inflammation which, for the oral epithelium, are traditionally provided by punch biopsies. To reduce patient discomfort and morbidity, we have developed a non-invasive alternative using diffuse reflectance spectroscopy. Though any optical system has the potential for probing near-surface structures, traditional methods of accounting for scattering of photons are generally invalid for typical epithelial thicknesses. We have previously developed a theory that is valid in this regime and validated it with Monte Carlo simulations. We use a differential measure with acute sensitivity to small changes in layer scattering coefficients. To assess the capability of the approach to quantify epithelial thickness, detailed Monte Carlo simulations and measurements on phantom models of a two layered structure have been performed. Preliminary results from this work show that our key feature varies less than 20 percent despite four-fold changes in scattering coefficients and ten-fold changes in absorption coefficients. This indicates that the method will be of practical clinical value for quantifying epithelial thickness in vivo .

A practical measurement system has been developed for creating an image of skin thermal properties using a stepwise change in ambient radiation temperature. By introducing a capacitor discharge circuit, more rapid stepwise change in ambient temperature was achieved, at a rate 30% faster than a mechanical system. Numerous experiments were performed using the authors' present system on the facial skin of the cheek. The repeatability of thermal properties of the same subject suggests that the present system is reliable for practical use.

An imaging system has been developed to visualize the effect of reactive hyperemia by measuring skin thermal inertia after releasing arterial occlusion because it was known that thermal inertia depends on the blood flow. The method is based on the ability to calculate thermal inertia from thermographic measurements of the response to a known stepwise change in ambient radiation temperature. Measurements were made during reactive hyperemia after 1 min of complete occlusion. After immediate releasing the cuff pressure, the response of reactive hyperemia appeared in the image of thermal inertia, where many island-shaped nonuniform thermal inertia distributions were observed.

Contamination of medical devices has become a critical and prevalent public health safety concern since medical devices are being increasingly used in clinical practices for diagnostics, therapeutics and medical implants. The development of effective sensing methods for real-time detection of pathogenic contamination is needed to prevent and reduce the spread of infections to patients and the healthcare community. In this study, a hollow-core fiber-optic Fourier transform infrared spectroscopy methodology employing a grazing incidence angle based sensing approach (FO-FTIR-GIA) was developed for detection of various biochemical contaminants on medical device surfaces. We demonstrated the sensitivity of FO-FTIR-GIA sensing approach for non-contact and label-free detection of contaminants such as lipopolysaccharide from various surface materials relevant to medical device. The proposed sensing system can detect at a minimum loading concentration of approximately 0.7 μg/cm(2). The FO-FTIR-GIA has the potential for the detection of unwanted pathogen in real time.

As a potential major source of biochemical contamination, medical device surfaces are of critical safety concerns in the clinical practice and public health. The development of innovative sensing methods for accurate and real-time detection of medical device surface contamination is essential to protect patients from high risk infection. In this paper, we demonstrate an alternative fiber-optic Fourier Transform Infrared (FTIR) spectroscopy based sensing approach for remote, non-contact, and label-free detection of biochemical contaminants in the mid-infrared (mid-IR) region. The sensing probe is designed using mid-IR hollow fibers and FTIR measurements are carried out in reflection mode. Bovine Serum Albumin (BSA) and bacterial endotoxin of different concentrations under thoroughly dry condition are used to evaluate the detection sensitivity. The devised system can identify ≤0.0025% (≤4 × 10(11) molecules) BSA and 0.5% (0.5 EU/ml) endotoxin concentration. The developed sensing approach may be applied to detect various pathogens that pose public health threats.