mHealth spectroscopy of blood hemoglobin with spectral super-resolution.

Although blood hemoglobin (Hgb) testing is a routine procedure in a variety of clinical situations, noninvasive, continuous, and real-time blood Hgb measurements are still challenging. Optical spectroscopy can offer noninvasive blood Hgb quantification, but requires bulky optical components that intrinsically limit the development of mobile health (mHealth) technologies. Here, we report spectral super-resolution (SSR) spectroscopy that virtually transforms the built-in camera (RGB sensor) of a smartphone into a hyperspectral imager for accurate and precise blood Hgb analyses. Statistical learning of SSR enables us to reconstruct detailed spectra from three color RGB data. Peripheral tissue imaging with a mobile application is further combined to compute exact blood Hgb content without a priori personalized calibration. Measurements over a wide range of blood Hgb values show reliable performance of SSR blood Hgb quantification. Given that SSR does not require additional hardware accessories, the mobility, simplicity, and affordability of conventional smartphones support the idea that SSR blood Hgb measurements can be used as an mHealth method.

Publisher Correction: Anderson light localization in biological nanostructures of native silk.

The original PDF version of this Article contained errors in Equations 1 and 2. Both equations omitted all Γ terms. This has been corrected in the PDF version of the Article. The HTML version was correct from the time of publication.

Anderson light localization in biological nanostructures of native silk.

Light in biological media is known as freely diffusing because interference is negligible. Here, we show Anderson light localization in quasi-two-dimensional protein nanostructures produced by silkworms (Bombyx mori). For transmission channels in native silk, the light flux is governed by a few localized modes. Relative spatial fluctuations in transmission quantities are proximal to the Anderson regime. The sizes of passive cavities (smaller than a single fibre) and the statistics of modes (decomposed from excitation at the gain-loss equilibrium) differentiate silk from other diffusive structures sharing microscopic morphological similarity. Because the strong reflectivity from Anderson localization is combined with the high emissivity of the biomolecules in infra-red radiation, silk radiates heat more than it absorbs for passive cooling. This collective evidence explains how a silkworm designs a nanoarchitectured optical window of resonant tunnelling in the physically closed structures, while suppressing most of transmission in the visible spectrum and emitting thermal radiation.

Data-driven imaging of tissue inflammation using RGB-based hyperspectral reconstruction toward personal monitoring of dermatologic health.

Sensitive and accurate assessment of dermatologic inflammatory hyperemia in otherwise grossly normal-appearing skin conditions is beneficial to laypeople for monitoring their own skin health on a regular basis, to patients for looking for timely clinical examination, and to primary care physicians or dermatologists for delivering effective treatments. We propose that mathematical hyperspectral reconstruction from RGB images in a simple imaging setup can provide reliable visualization of hemoglobin content in a large skin area. Without relying on a complicated, expensive, and slow hyperspectral imaging system, we demonstrate the feasibility of determining heterogeneous or multifocal areas of inflammatory hyperemia associated with experimental photocarcinogenesis in mice. We envision that RGB-based reconstructed hyperspectral imaging of subclinical inflammatory hyperemic foci could potentially be integrated with the built-in camera (RGB sensor) of a smartphone to develop a simple imaging device that could offer affordable monitoring of dermatologic health.

Telecentric suppression of diffuse light in imaging of highly anisotropic scattering media.

The telecentric lens, which was originally used in the machine vision industry, has often been utilized in biomedical imaging systems due to its commonly known properties, such as large transverse field of view, constant magnification, and long working distance. However, its potential advantages in optical imaging of biological tissue, which is highly diffusive, have not been fully explored. We revisit the idea that a telecentric lens system can bring an alternative yet simple method for reducing unwanted scattering or diffuse light in biological tissue, owing to its highly anisotropic scattering properties. Using biological tissue and tissue phantoms, we demonstrate advantages attributed to the use of telecentric lens in tissue imaging compared with imaging using conventional nontelecentric optics. Directional or angular gating (or filtering) using a telecentric lens is beneficial for removing a portion of diffuse light in highly anisotropic scattering media with high values of the scattering anisotropy factor. We envision that a telecentric lens could be potentially incorporated into an instrument of modest design and cost, increasing rapid practical adoption.

Direct analysis of melamine in complex matrices using a handheld mass spectrometer.

A low temperature plasma ambient ionization source, coupled to a portable mass spectrometer (Mini 10.5), is used for the determination of melamine contamination in whole milk and related materials. Thermally assisted desorption and ionization of the analyte was achieved with the plasma probe. The small size, low power consumption and capability for direct sampling without pretreatment makes plasma ionization an appropriate ionization method for use with a handheld mass spectrometer. The standard discontinuous atmospheric pressure interface used to connect atmospheric pressure ion sources to mass spectrometers (Gao et al., Anal. Chem., 2008, 80, 4026-4032) was modified by using supplementary pumping to increase the ion transfer efficiency. Whole milk, fish, milk powder and other complex matrices spiked with melamine were placed on glass slides close to the vacuum inlet and analyzed without sample pretreatment. Quantitation in complex matrices was achieved using MS/MS of protonated melamine m/z 127 to yield the characteristic fragment ion of m/z 85. Analysis rates of two samples per minute, levels of melamine as low as 250 ng/mL in whole milk (below the regulatory level in the US of 1 ppm (1 microg/mL) or the European level of 2.5 ppm (microg/mL)), a linear dynamic range of 0.5-50 microg/mL and a relative standard deviation of ca. 7.6-16.2% were achieved. The importance of melamine to public health and the prior lack of a rapid, sensitive and yet highly specific field analysis method add to the relevance of this study.