[Resonance wavelength effects on sensitivity of resonant grating waveguide biosensor].

Resonant grating waveguide (RGW) biosensor has been widely investigated in recent years. The system has several advantages such as minimizing, label-free, high throughput, real time monitoring and so on. The sensitivity of RGW biosensor was theoretically analyzed for different resonance wavelength. Sensitivity to the refractive index and thickness of the sample was analyzed using rigorous coupled wave analysis method. Results indicate that the sensitivity to refractive index is constant for a certain resonance wavelength as the thickness of sample does not change. The sensitivity to refractive index is enhanced with the increase of resonance wavelength. RGW with 1 250 nm resonance wavelength is approximately 4 times as sensitive as RGW with 830 nm resonance wavelength. The sensitivity to thickness drastically decreased at first, and then achieved zero for a certain resonance wavelength as the refractive index of sample is invariable. It was showed that it is limited to test sample thickness for every RGW. RGW with 1 250 nm resonance wavelength is approximately 2 times the measure range as RGW with 830 nm resonance wavelength. The sensitivity to thickness is enhanced with the increase of resonance wavelength. RGW with 1 250 nm resonance wavelength is approximately 3 times as sensitive as RGW with 830 nm resonance wavelength. The above results reveal that the sensitivity to both sample refractive index and sample thickness is enhanced with the increase of resonance wavelength. And the capability of testing sample thickness improves with longer resonance wavelength. The results provided the theory basis for resonance wavelength choice of RGW biosensor.

Optimal classification for the diagnosis of duchenne muscular dystrophy images using support vector machines.

BACKGROUND: This study aimed to investigate the optimal support vector machines (SVM)-based classifier of duchenne muscular dystrophy (DMD) magnetic resonance imaging (MRI) images. METHODS: T1-weighted (T1W) and T2-weighted (T2W) images of the 15 boys with DMD and 15 normal controls were obtained. Textural features of the images were extracted and wavelet decomposed, and then, principal features were selected. Scale transform was then performed for MRI images. Afterward, SVM-based classifiers of MRI images were analyzed based on the radical basis function and decomposition levels. The cost (C) parameter and kernel parameter [Formula: see text] were used for classification. Then, the optimal SVM-based classifier, expressed as [Formula: see text]), was identified by performance evaluation (sensitivity, specificity and accuracy). RESULTS: Eight of 12 textural features were selected as principal features (eigenvalues [Formula: see text]). The 16 SVM-based classifiers were obtained using combination of (C, [Formula: see text]), and those with lower C and [Formula: see text] values showed higher performances, especially classifier of [Formula: see text]). The SVM-based classifiers of T1W images showed higher performance than T1W images at the same decomposition level. The T1W images in classifier of [Formula: see text]) at level 2 decomposition showed the highest performance of all, and its overall correct sensitivity, specificity, and accuracy reached 96.9, 97.3, and 97.1 %, respectively. CONCLUSION: The T1W images in SVM-based classifier [Formula: see text] at level 2 decomposition showed the highest performance of all, demonstrating that it was the optimal classification for the diagnosis of DMD.

Endoscopic swept-source optical coherence tomography based on a two-axis microelectromechanical system mirror.

A microelectromechanical system (MEMS) mirror based endoscopic swept-source optical coherence tomography (SS-OCT) system that can perform three-dimensional (3-D) imaging at high speed is reported. The key component enabling 3-D endoscopic imaging is a two-axis MEMS scanning mirror which has a 0.8×0.8 mm2 mirror plate and a 1.6×1.4 mm2 device footprint. The diameter of the endoscopic probe is only 3.5 mm. The imaging rate of the SS-OCT system is 50 frames/s. OCT images of both human suspicious oral leukoplakia tissue and normal buccal mucosa were taken in vivo and compared. The OCT imaging result agrees well with the histopathological analysis.