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Current commercially fielded approaches for detection of trace materials (explosives, narcotics, low volatility chemical warfare agents and other hazardous chemicals) on surfaces require physical collection and analysis of the trace material. Although these techniques are very sensitive, they require unseen particles to be collected from the surface of the substrate being screened and be transferred to the analysis system. This collection process requires human input (and close-proximity exposure to the screened article, which could pose a safety threat), introduces a fundamental limit on the screening speed, and limits the types of surfaces that can be successfully tested for trace materials to those with good “wipe-ability”. The Intelligence Advanced Research Projects Activity (IARPA) SILMARILS program has demonstrated the capability to detect trace explosives at levels comparable with Explosive Trace Detection (ETD) systems, and narcotics at similar levels. This paper details the algorithms and sensor advances that have enabled these results. A number of relevant experimental test campaigns are discussed including: detection of target chemicals on harvested “real world” substrates such as wood, auto tires, smooth and rough metal, plastics, vinyl, leather, various fabrics, and pig skin (comparable to human skin with respect to fat, water, and hemoglobin content); detection of traces of explosives on portable electronic devices (including after cleaning with organic solvents); and field testing at the 2019 Indianapolis 500 race, where incoming spectator vehicles were screened for explosives simulants (with blind positive controls provided by test and evaluation team rental cars).

Dermal fillers are a very popular anti-ag ing treatment with estimated sales in the billions of dollars and millions of procedures performed. As the aging population continues to grow, these figures are only e xpected to increase. Dermal fillers have various compositions depending on their intended applicati on. Reactions to dermal fillers can be severe, such as ischemic events and filler migration to the eyes. Howe ver, these adverse reactions are rare. Nevertheless, the capability to perform imag e-guided filler injections would minimize th e risk of such reacti ons. In addition, the biomechanical properties of various fillers have been evalua ted, but there has been no investigation on the effects of filler on the biomechanical properties of skin. In this work, we utilize optical cohe rence tomography (OCT) for visualizing dermal filler injections with micrometer-scale sp atial resolution. In addition, we utilize noncontact optical coherence elastography (OCE) to quantify the changes in the biomechan ical properties of pig skin after the dermal filler injections. OCT was successfully able to visualize the dermal filler injecti on process, and OCE showed that the viscoelasticity of the pig skin was increased locally at the filler injection sites. OCT may be able to provide real-time image guidance in 3D, and when combined with functional OCT techniques such as optical microangiography, could be used to avoid blood vessels during the injection.

Skin cholesterol is a novel biomarker to assess the risk of atherosclerotic diseases. To detect skin cholesterol noninvasively and rapidly, a system was designed based on the diffuse reflectance spectroscopy. The feasibility of this system was validated through detecting cholesterol of pig skin samples, and skin cholesterol in vivo of subjects. The experimental results showed that, diffuse reflectance absorbance integrated intensity S measured the concentration of cholesterol in the pig skin samples quantitatively. After adjusting for age, gender and other factors, it showed a significant positive correlation between S of subjects and the total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) which were the main risk factors for atherosclerotic diseases with the correlation coefficients 0.860(P

Interstitial fluid (ISF) can be transdermally extracted using low-frequency ultrasound and continuous vacuum pressure on skin surface. But the tiny volume of transdermally extracted ISF makes the transdermal extraction, collection, transport, volumetric detection and glucose concentration measurement of the ISF very difficult. Based on a microfluidic chip for transdermally extraction of interstitial fluid and a micro glucose sensor for glucose concentration measurement, a continuous glucose monitoring instrumentby ISF transdermal extraction with minimally invasive way is developed. In the paper, various parts of the device and their interface circuits are designed; the hardware and software of the instrument are built; the simulating experiments of transdermal ISF extraction, collection and volume measurement with full-thickness pig skin are performed using this integrated system; and the functionalities of this device is verified for future clinical application.

For the fist time worldwide we report high amplitude NIR-Luminescence signals, measured in pig skin. The measurements are achieved with a recently developed setup that was shown to provide superior performance for 1O2- luminescence detection in vitro. This setup has been adapted to allow now the detection of singlet oxygen signals in vivo. Pig ears were used for first measurements as a widely accepted in vivo model for human skin.

In present study we have considered diffusion of immersion agent into the skin through thermally pretreated stratum corneum solving the corresponding diffusion problem. Algorithm of refractive index of interstitial liquid and diffusion coefficient of immersion agent into biotissue estimations at a creation of lattice-like pattern of localized thermal damage islets in the stratum corneum, was develop. Theoretical model which sufficiently describes the influence of immersion agents on skin optical properties was presented. The diffusion coefficient of glycerol into pig skin ex vivo at creating a lattice of islets of damage in the stratum corneum is 0.84±0.08 μm2/s.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Existing noninvasive imaging modalities fail to provide high-resolution depth-resolved imaging of skin burns in large depths. Hence, the measurement of burn depth, especially for partial-thickness burn, remains inaccurate. We used photoacoustic microscopy to measure the depth of acute thermal burns by imaging the microvasculature damage. In this work, partial-thickness burns were induced in vivo on pig skin. Limited by the flexibility of the photoacoustic scanning system, photoacoustic images of the burns were acquired after skin excision. Experimental results show that burn depth increases with longer heating duration. The maximum imaged burn depth measures ∼1.7 mm with a depth resolution of 15 µm.

The purpose of this study was to evaluate the laser-tissue interactions of engineered human skin and in-vivo pig skin following exposure to a single 3.8 micron laser light pulse. The goal of the study was to determine if these tissues shared common histologic features following laser exposure that might prove useful in developing in-vitro and in-vivo experimental models to predict the bioeffects of human laser exposure. The minimum exposure required to produce gross morphologic changes following a four microsecond, pulsed skin exposure for both models was determined. Histology was used to compare the cellular responses of the experimental models following laser exposure. Eighteen engineered skin equivalents ( in-vitro model), were exposed to 3.8 micron laser light and the tissue responses compared to equivalent exposures made on five Yorkshire pigs ( in-vivo model). Representative biopsies of pig skin were taken for histologic evaluation from various body locations immediately, one hour, and 24 hours following exposure. The pattern of epithelial changes seen following in-vitro laser exposure of the engineered human skin and in-vivo exposure of pig skin indicated a common histologic response for this particular combination of laser parameters.

Two temperature controlled laser soldering systems were compared, one based on a GaAs laser and the other on a CO2 laser. Both systems were used for bonding full thickness incisions. Methods: 47% bovine serum albumin (BSA) solder was used in the CO2 laser soldering experiments. BSA with 1.8 mg/ml Indocyanine Green (ICG) was used for the GaAs soldering experiments. In both cases the solder was applied onto cuts created in juvenile pig skin and an infrared fiberoptic system was used to monitor and control different temperature and time settings. Differences in tensile strength and wound reparative parameters were compared between GaAs laser, CO2 laser, and Dermabond glued incisions on the seventh day after the operation. Results: The tensile strength of CO2 laser-soldered and Dermabond glued incisions were found to be higher than that of the GaAs laser-soldered incisions. Histological study showed better and faster wound healing characteristics of the CO2 laser soldered incisions, as compared to the GaAs laser-soldered and glued incisions. Conclusions: Preliminary results of temperature controlled CO2 laser soldered incisions suggest a better wound reparative process over the temperature controlled GaAs laser soldered incisions. Laser soldering offers many advantages over gluing techniques.

Background and objectives: A feedback temperature controlled laser soldering system was used for bonding cut wounds on the skins of young and mature pigs. This is a step towards clinical implantation of this promising novel technique. Materials and methods: 47% bovine serum albumin (BSA) solder was applied onto cuts created in dorsally d epilated skin on the backs of pigs, weighing 8 -10Kg or 74Kg. A temperature fiberoptic CO2 laser system was used to monitor and control the temperature of a spot on the cut at a desired temperature. For given values of time and temperature, a 28 days follow up of the soldered scars was obtained and compared with standard suturing. Results: Optimal soldering temperature was found to be 65oC. The tensile strength of laser-soldered cuts was measured after 3-28 days postoperatively and was found similar to that of sutured cuts. Macroscopic and microscopic studies showed better and faster wound healing of soldered scars compared with standard sutures. All soldered scars in the mature pig, demonstrated excellent healing with no signs of dehiscence. Conclusions: Temperature controlled laser soldering of cut wounds in pig skin offers several advantages over standard suturing techniques. This novel method should be tested clinically.

Progress towards a painless and hygienic glucose monitoring procedure for diabetics continues as the growth of diabetes mellitus reaches epidemic proportions in the American population. Utilizing an implantable fluorescence based glucose assay, the minimally invasive approach presented here has previously shown promise towards this goal in terms of glucose specificity and quantification for in vitro environments. However, in realistic physiological circumstances the depth of the implant can vary and optical properties of skin can change due to normal physiological conditions. Additionally, naturally occurring auto-fluorescence can obscure the sensor signal. An important concern under these conditions is that variations of fluorescent intensity due to these or other causes might be mistaken for glucose concentration fluctuations. New data shows that fluorescence-based glucose assays can be probed and interpreted in terms of glucose concentrations through pig skin at depths of up to 700 mm when immobilized in a bio-compatible polymer. When a combination of two fluorophores are employed as demonstrated here, reasonable changes in skin thickness and the confounding effects of the variations inherent in skin can be overcome for this glucose sensing application.

Residual thermal damage produced by a scanned quasi cw CO 2 laser was measured in pig skin. The effects of scan speed on thermal damage distribution for laser dwell times ranging between 1 and 150 msec were examined. Significantly larger thermal damage zones were produced along the crater wall for laser dwell times longer than 50 msec. Thermal damage along the crater base was constant independent of dwell time. The preliminary experimental results suggest that quasi cw CO 2 can consistently produce less than 200 micrometers zones of thermal damage if laser parameters are carefully chosen.

Selective damage of epidermal pigment cells induced by 504 nm pulsed dye laser at different pulse durations and fluence on black pig skin was examined electron microscopically. Epidermal melanosomes were satisfactorily disrupted at shorter pulse duration (100 ns). Epidermal blister formation and necrosis were seen at 2 days postirradiation, and reepithelization was evident at 7 days postirradiation in all specimens. Repigmentation was evident 21 to 56 days after irradiation. Histological pigmentary incontinence was evident at 2 days and persisted until 56 days postirradiation. This phenomenon was observed more frequently in skin exposed to longer pulse duration and at low fluences. Optimal parameters required to induce epidermal melanosome disruption using the 504 nm pulsed dye laser will be discussed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have demonstrated that 11cNc, laws stimulate collagen synthesis both in human stun fibroblast cultures and hairless mice in vivo. Subscqucnt studies on pig skin have also idcntificd the mechanism of the collagen stimulation. Both type 1 and typc 111 procolagcn mRNA, levels were markcdly elevated at day 17 and 26 in wounds treated by laser. Furthermore, typo ill procollagen was cicvatcd in carly stages of wound healing, at day 10, confirming the notion that typc 111 collagen accumulation precedes that of typc 1 in wound healing processes. (for summary,please see table and references below)