Spectrometer-based wavelength interrogation SPR imaging via Hadamard transform.

We present spectrometer-based wavelength interrogation surface plasmon resonance imaging (SPRi) without mechanical scanning. A polarized broadband light source illuminates an object via a gold-coated prism; the reflected light is spatially modulated by a digital mirror device (DMD) and then measured with a spectrometer. Reflectance spectral images are reconstructed via the Hadamard transform (HT), and a refractive index (RI) map is visualized from the reflectance spectral images by analyzing the resonance peak shift of the spectrum at each image pixel. We demonstrate the feasibility of our method by evaluating the resolution, sensitivity, and dynamic detection range, experimentally obtained as ∼2.203 × 10-6 RI unit (RIU), ∼3,407 nm/RIU, and ∼0.1403 RIU, respectively. Furthermore, simulations are performed to validate the experimental results.

PLC-Based Integrated Refractive Index Sensor Probe with Partially Exposed Waveguide.

This paper proposes a simple, high-efficiency refractive index (RI) sensor, with a structure based on the planar lightwave circuit (PLC) probe type. The optical sensor has a 1 × 2 splitter structure with reference and sensing channels, each consisting of a U-shaped waveguide structure that is configured by connecting C bends. This design allows for the sensor device to have a probe structure wherein the surface interconnected with activity devices (i.e., an optical source and optical detector) is placed on one side. The reference channel is bent with a minimum optical loss, and the sensing channel has a bent structure, involving a C-bend waveguide with a maximum loss. The C-bend waveguide with a maximum loss is conformally aligned to have a trench structure with the same bending radius, designed to selectively expose the sidewall of the core layer. The local index contrast varies depending on the material in contact with the trench, resulting in a change in the optical output power of the waveguide. The sensitivity of the proposed sensor was 0 and 2070 µW/refractive index unit (RIU) for the reference and sensing channels, respectively, as the RI changed from 1.385 to 1.445 at a 1550 nm wavelength. These results suggest that the proposed structure enables efficient RI measurement through the use of a simple dip-type method.

Polarization-sensitive differential phase-contrast microscopy.

We present a novel, to the best of our knowledge, form of polarization microscopy capable of producing quantitative optic-axis and phase retardation maps of transparent and anisotropic materials. The proposed method operates on differential phase-contrast (DPC) microscopy that produces a phase image of a thin specimen using multi-axis intensity measurements. For polarization-sensitive imaging, patterned illumination light is circularly polarized to illuminate a specimen. The light transmitted through a specimen is split into two orthogonal polarization states and measured by an image sensor. Subsequent DPC computation based on the illumination patterns, acquired images, and the imaging model enables the retrieval of polarization-dependent quantitative phase images, which are utilized to reconstruct the orientation and retardation of the specimen. We demonstrate the validity of the proposed method by measuring the optic-axis and phase retardation maps of calibrated and various anisotropic samples.

Single-pixel, single-input-state polarization-sensitive wavefront imaging.

In this Letter, we describe a single-pixel polarization-sensitive imaging technique, capable of generating the birefringence map of a thin specimen by using single-pixel detectors. Spatially modulated light is circularly polarized to illuminate the specimen. The transmitted light through the specimen is then focused via a lens and measured by position-sensitive detectors in two orthogonal polarization channels. The measurement of the irradiance and centroid position of the optical focus and subsequent computations enable the production of polarization-dependent wavefront maps, which can then be utilized to reconstruct sample birefringence information. We demonstrate the feasibility of our method by measuring distribution of optic-axis orientation and phase retardation of various birefringent samples.

Miniaturized Sample Preparation and Rapid Detection of Arsenite in Contaminated Soil Using a Smartphone.

Conventional methods for analyzing heavy metal contamination in soil and water generally require laboratory equipped instruments, complex procedures, skilled personnel and a significant amount of time. With the advancement in computing and multitasking performances, smartphone-based sensors potentially allow the transition of the laboratory-based analytical processes to field applicable, simple methods. In the present work, we demonstrate the novel miniaturized setup for simultaneous sample preparation and smartphone-based optical sensing of arsenic As(III) in the contaminated soil. Colorimetric detection protocol utilizing aptamers, gold nanoparticles and NaCl have been optimized and tested on the PDMS-chip to obtain the high sensitivity with the limit of detection of 0.71 ppm (in the sample) and a correlation coefficient of 0.98. The performance of the device is further demonstrated through the comparative analysis of arsenic-spiked soil samples with standard laboratory method, and a good agreement with a correlation coefficient of 0.9917 and the average difference of 0.37 ppm, are experimentally achieved. With the android application on the device to run the experiment, the whole process from sample preparation to detection is completed within 3 hours without the necessity of skilled personnel. The approximate cost of setup is estimated around 1 USD, weight 55 g. Therefore, the presented method offers the simple, rapid, portable and cost-effective means for onsite sensing of arsenic in soil. Combined with the geometric information inside the smartphones, the system will allow the monitoring of the contamination status of soils in a nation-wide manner.

Frequency- and spectrally-encoded confocal microscopy.

We describe a three-dimensional microscopy technique based on spectral and frequency encoding. The method employs a wavelength-swept laser to illuminate a specimen with a spectrally-dispersed line focus that sweeps over the specimen in time. The spatial information along each spectral line is further mapped into different modulation frequencies. Spectrally-resolved detection and subsequent Fourier analysis of the back-scattered light from the specimen therefore enable high-speed, scanner-free imaging of the specimen with a single-element photodetector. High-contrast, three-dimensional imaging capability of this method is demonstrated by presenting images of various materials and biological specimens.

Association between BH3 interacting domain death agonist (BID) gene polymorphism and ossification of the posterior longitudinal ligament in Korean population.

The purpose of this study was to investigate single nucleotide polymorphisms (SNPs) of the BH3 interacting domain death agonist (BID) gene as a risk factor in Korean patients with ossification of the posterior longitudinal ligament (OPLL). To investigate the genetic association, two coding SNPs (rs8190315, Ser10Gly; rs2072392, Asp60Asp) of BID were genotyped in 157 OPLL patients and 209 control subjects. SNPStats, SNPAnalyzer Pro, Helixtree, and Haploview 4.2 programs were used for association analysis. Multiple logistic regression models (codominant, dominant, and recessive) were calculated for the odds ratios (ORs), 95 % confidence intervals (CIs), and corresponding P values. For multiple testing, Bonferroni correction was performed. After Bonferroni correction, genotype analysis of both rs8190315 and rs2072392 showed association between the OPLL group and the control group in the codominant model (P = 0.042, OR 1.86, 95 % CI 1.10-3.15). A complete linkage disequilibrium block was estimated between the two SNPs. Both of the G allele of rs8190315 and C allele of rs2072392 were strongly associated with an increased risk in the development of OPLL (P = 0.0052, OR 2.66, 95 % CI 1.51-4.68). These results suggest that BID is associated with OPLL, and both the G allele of a missense SNP (rs8190315, Ser10Gly) and C allele of a synonymous SNP (rs2072392, Asp60Asp) are risk factors for the development of OPLL in Korean population.

Surgical treatment for intra-thoracic migration of acupuncture needles.

The aim of this study was to introduce the experience of diagnosis and treatment for patients with migrated acupuncture needle to pleural cavity and or lung parenchyma. We had treated 5 patients who had acupuncture needles in their thoracic cavity from January 2000 to September 2009. The mean age was 55.8 yr old. All patients suffered from the sequelae of the cerebrovascular accident and had been treated with acupuncture. They had drowsiness and hemiplegic or quadriplegic motor activity. Fever and dyspnea were main symptoms when referred to us. Diagnosis was made by the chest radiography and chest computed tomography which revealed straight metallic materials in their thoracic cavity. The needles were removed via thoracotomy or thoracoscopic procedures. Pleural decortications were also needed in four patients. Thoracoscopic surgery was successfully performed in two patients. After the removal all patients became symptomless. Although we experienced only five patients who have migrated acupuncture needles in thoracic cavity, we suggest that thoracoscopic removal of the needle with or without pleural decortication is the most optimal modality of treatment in those patients.

A Portable Smartphone-linked Device for Direct, Rapid and Chemical-Free Hemoglobin Assay.

We describe the development and clinical evaluation of an automated smartphone-linked sensor capable of chemical-free, quantitative measurement of hemoglobin concentration ([Hb]) in whole blood samples. We have demonstrated that our sensor could analyze an unprocessed blood specimen with a mean processing time of <8 s and provided the [Hb] results with ~99% accuracy against a reference hematology analyzer with coefficient of variation (CV) of 1.21% measured at [Hb] = 11.2 g/dL. Its diagnostic capability for anemia was evaluated by measuring [Hb] of 142 clinical blood specimens and comparing the results with those from an automated hematology analyzer (ADVIA 2120i, Siemens AG, Germany) and a portable hemoglobinomteter (Hb201+, Hemocue, Sweden). The sensor yielded comparable sensitivities and specificities of 87.50% and 100.00% for males, and 94.44% and 100.00% for females, respectively, for anemic detection. The results suggested that our optical sensor based on the intrinsic photothermal response of Hb molecules and advances in consumer electronics, particularly smartphone capabilities, enables a direct, chemical-free [Hb] assay accessible to people in both developed and developing countries.

Smart Fatigue Phone: Real-time estimation of driver fatigue using smartphone-based cortisol detection.

Numerous studies reported that psychological fatigue is one of the main reasons leading fatal road crashes. In order to quantify fatigue level of each subject, we measured a concentration of salivary cortisol from 4 subjects (20-40 years of age) using the Smart Fatigue Phone, which consists of a lateral flow immunosensor and a smartphone-linked fluorescence signal reader, during 50-min driving session. Since the salivary cortisol needs to be measured below 1 ng/mL to distinguish the subjects from awaken-drivers, we have employed the fluorescence detection module (Limit of detection: 0.1 ng/mL). To validate correlation between fatigue status and salivary cortisol concentration measured by the Smart Fatigue Phone, the electroencephalogram (EEG) signal was simultaneously obtained from the participants. As a result, alpha wave and concentration of cortisol over time was highly correlated, reflecting that quantification of salivary cortisol can be used for real-time monitoring of driver fatigue (p < 0.05). The Smart Fatigue Phone is expected to be a useful tool for drivers to recognize their fatigue status and subsequently to make a decision for driving a car. Thus, we assume that this fatigue detection system will consequently minimize road crashes by quantifying salivary cortisol in real time in the near future.

Highly sensitive paper-based immunoassay using photothermal laser speckle imaging.

Paper-based lateral-flow assay (LFA) is a simple and inexpensive point-of-care device that has become commonplace in medicine, environmental monitoring, and over-the-counter personal use. Some LFAs have demonstrated comparable analytical performance with laboratory-based methods, but the detection limit or sensitivity of most LFAs is significantly inferior to other molecular techniques by 10-100 × . Consequently, LFAs are not viable for the early detection of disease-relevant biomarkers that are present in extremely small amounts in clinical specimens. Herein, we present a simple, cost-effective, and highly sensitive LFA sensor based on photothermal laser speckle imaging (PT-LSI). Under the illumination of a photothermal excitation light, gold nanoparticles (AuNPs), a common signal transduction medium in LFAs, absorb the light energy to produce heat, which subsequently induces modulation of the optical property and thermal deformation of the membrane. We measured these fluctuations through laser speckle imaging to quantify the concentration of AuNP-biomarker complexes. We experimentally demonstrate that the detection limit of our technique is superior to that of colorimetric detector by 68-125 × . The capability of our sensor for highly sensitive detection of disease biomarkers is validated by using U.S. FDA-approved LFA kits for cryptococcal antigens (CrAg).

Smartphone-based multi-contrast microscope using color-multiplexed illumination.

We present a portable multi-contrast microscope capable of producing bright-field, dark-field, and differential phase contrast images of thin biological specimens on a smartphone platform. The microscopy method is based on an imaging scheme termed "color-coded light-emitting-diode (LED) microscopy (cLEDscope)," in which a specimen is illuminated with a color-coded LED array and light transmitted through the specimen is recorded by a color image sensor. Decomposition of the image into red, green, and blue colors and subsequent computation enable multi-contrast imaging in a single shot. In order to transform a smartphone into a multi-contrast imaging device, we developed an add-on module composed of a patterned color micro-LED array, specimen stage, and miniature objective. Simple installation of this module onto a smartphone enables multi-contrast imaging of transparent specimens. In addition, an Android-based app was implemented to acquire an image, perform the associated computation, and display the multi-contrast images in real time. Herein, the details of our smartphone module and experimental demonstrations with various biological specimens are presented.

Random lasing from structurally-modulated silk fibroin nanofibers.

Structural arrangement and dimension play vital roles in wave transport and amplification as they can restrict the volume explored by the waves. However, it is challenging to systematically investigate the interplay among structural, optical, and mechanical properties, in part because of limited experimental platforms that modulate the structural arrangement in a continuous manner. We present light amplification action in Rhodamine B doped silk fibroin (SF) nanofibrous scaffolds and its modulation via the control of the alignment or directionality of SF nanofibers through an electrospinning procedure. Random lasing features of such scaffolds are examined as a function of structural arrangement of the SF nanofibers, and optical-structural-mechanical relationships of the SF-based structures are examined. As SF nanofibers are aligned parallel undergoing a transition from three to quasi-two dimension, light amplification features (e.g., lasing threshold and output power) enhanced, which also strongly correlated with mechanical characteristics (i.e., Young's moduli) of the scaffolds. We confirm such optical characteristics using quasi-mode analyses based on the finite element method. We further demonstrate non-contact, in situ measurement of alternations in lasing features of the scaffolds while the specimens are under tensile loads. These results may highlight potential utility of the scaffolds as a flexible and biocompatible sensor.

Surgical strategy for pulmonary coarctation in the univentricular heart.

OBJECTIVE: The placement of a modified Blalock-Taussig shunt in patients suffering from pulmonary coarctation can result in the aggravation of uneven pulmonary blood flow. This may subsequently obviate the possibility of future performance of the Fontan procedure. The objective of this study was to evaluate mid-term results in patients with pulmonary coarctation who had undergone the placement of a modified Blalock-Taussig shunt, coupled with a pulmonary artery angioplasty. METHODS: We retrospectively reviewed the records of 13 patients who had undergone the placement of a modified Blalock-Taussig shunt, coupled with concomitant pulmonary angioplasty, between September 1998 and August 2002. All patients received follow-up angiographic evaluations. RESULTS: On the ipsilateral side of the modified Blalock-Taussig shunt, we observed a significant increase in the pulmonary artery index during a mean follow-up period of 11+/-5 months (preoperative 82+/-37 mm2/m2, follow-up 129+/-57, p=0.03). On the contralateral side, we also observed a significant increase in the pulmonary artery index (preoperative 90+/-56 mm2/m2, follow-up 137+/-56, p=0.047). There was one late death. During the follow-up period (mean 23+/-18 months), 10 patients received either a bidirectional or total cavopulmonary shunt and five of these patients underwent extracardiac Fontan operations. CONCLUSIONS: Our study demonstrated that the placement of a modified Blalock-Taussig shunt, with concomitant pulmonary artery angioplasty, constitutes a good initial surgical strategy in cases of univentricular heart with pulmonary coarctation.

Pericardial synovial sarcoma presenting with large recurrent pericardial effusion.

Primary pericardial synovial sarcoma is an extremely rare disease with a dismal prognosis. Its main presenting symptoms are a large pericardial effusion, signs of cardiac tamponade, and visualization of a pericardial mass on echocardiography. However, the systemic symptoms of fever, cough, and night sweats may present a clinical picture without any apparent pericardial mass on diagnostic imaging, potentially impeding the diagnosis. We report the case of a 34-year-old patient with fever and recurrent pericardial effusion for 2 years, who was diagnosed with primary pericardial synovial sarcoma after 2-year follow-up echocardiography.

A Rapid and Chemical-free Hemoglobin Assay with Photothermal Angular Light Scattering.

Photo-thermal angular light scattering (PT-AS) is a novel optical method for measuring the hemoglobin concentration ([Hb]) of blood samples. On the basis of the intrinsic photothermal response of hemoglobin molecules, the sensor enables high-sensitivity, chemical-free measurement of [Hb]. [Hb] detection capability with a limit of 0.12 g/dl over the range of 0.35 - 17.9 g/dl has been demonstrated previously. The method can be readily implemented using inexpensive consumer electronic devices such as a laser pointer and a webcam. The use of a micro-capillary tube as a blood container also enables the hemoglobin assay with a nanoliter-scale blood volume and a low operating cost. Here, detailed instructions for the PT-AS optical setup and signal processing procedures are presented. Experimental protocols and representative results for blood samples in anemic conditions ([Hb] = 5.3, 7.5, and 9.9 g/dl) are also provided, and the measurements are compared with those from a hematology analyzer. Its simplicity in implementation and operation should enable its wide adoption in clinical laboratories and resource-limited settings.

Capillary-scale direct measurement of hemoglobin concentration of erythrocytes using photothermal angular light scattering.

We present a direct, rapid and chemical-free detection method for hemoglobin concentration ([Hb]), based on photothermal angular light scattering. The iron oxides contained in hemoglobin molecules exhibit high absorption of 532-nm light and generate heat under the illumination of 532-nm light, which subsequently alters the refractive index of blood. We measured this photothermal change in refractive index by employing angular light scattering spectroscopy with the goal of quantifying [Hb] in blood samples. Highly sensitive [Hb] measurement of blood samples was performed by monitoring the shifts in angularly dispersed scattering patterns from the blood-loaded microcapillary tubes. Our system measured [Hb] over the range of 0.35-17.9 g/dL with a detection limit of ~0.12 g/dL. Our sensor was characterized by excellent correlation with a reference hematology analyzer (r>0.96), and yielded a precision of 0.63 g/dL for a blood sample of 9.0 g/dL.

Spectrally encoded slit confocal microscopy using a wavelength-swept laser.

We present an implementation of spectrally encoded slit confocal microscopy. The method employs a rapid wavelength-swept laser as the light source and illuminates a specimen with a line focus that scans through the specimen as the wavelength sweeps. The reflected light from the specimen is imaged with a stationary line scan camera, in which the finite pixel height serves as a slit aperture. This scanner-free operation enables a simple and cost-effective implementation in a small form factor, while allowing for the three-dimensional imaging of biological samples.

Staged biventricular repair of Taussig-Bing anomaly with subaortic stenosis and coarctation of aorta.

We present successful procedures for 2 infants who had the Taussig-Bing anomaly with subaortic stenosis and coarctation of the aorta. The initial procedure was coarctoplasty and the Damus-Kaye-Stansel procedure with modified Blalock-Taussig shunt. The second procedure was intraventricular repair (Kawashima procedure), Damus-Kaye-Stansel take-down and the reuse of native aortic and pulmonary valves 19 and 25 months later. Both patients survived the operations and postoperative hemodynamics were excellent at both 28 and 59 months follow-ups.

Truncus arteriosus with coarctation of persistent fifth aortic arch.

Truncus arteriosus is a rare form of congenital heart defect. Among cases, 10% to 20% are associated with arch anomalies, such as interruption, coarctation, or patent ductus arteriosus. We treated a rare case of combined truncus with complex arch anomaly. The patient was a 2-month-old girl weighing 3.8 kg. Echocardiogram and computed tomogram showed interrupted aortic arch, truncus arteriosus, persistent fifth aortic arch, and its coarctation. One-stage total correction was performed under cardiopulmonary bypass without circulatory arrest. The operation consisted of a Rastelli procedure with a 12-mm valved conduit, coarctoplasty, and intraventricular baffling. The patient recovered well without complications.