Abstract
Optical characterization and internal structure of biological tissues is highly important for biomedical optics. In particular for optical clearing processes, such information is of vital importance to understand the mechanisms involved through the variation of the refractive indices of tissue components. The skeletal muscle presents a fibrous structure with an internal arrangement of muscle fiber cords surrounded by interstitial fluid that is responsible for strong light scattering. To determine the refractive index of muscle components we have used a simple method of measuring tissue mass and refractive index during dehydration. After performing measurements for natural and ten dehydration states of the muscle samples, we have determined the dependence between the refractive index of the muscle and its water content. Also, we have joined our measurements with some values reported in literature to perform some calculations that have permitted to determine the refractive index of the dried muscle fibers and their corresponding volume percentage inside the natural muscle.

Abstract
Movement quantification of the human body is presently used for analyzing deficits resulting from Central Nervous System (CNS) pathologies or exploring the insights of the human motor system behaviour. Following our previous work on 2D movement quantification of epileptic seizures, we now present a feasibility study for a newly developed 3D technique. In order to validate this new 3D approach we made a comparison with the previous method. Both techniques were tested in two different datasets: a simple motor execution performed by a volunteer and a complex motor motion induced by a real epileptic seizure. The results obtained showed, as expected, the superior robustness and precision of the 3D approach but also confirmed the validity of the 2D method, given certain constraints. We conclude that the newly developed 3D system will highly improve our capacity of pursuing the clinical research on quantitative characterization of seizure semiology to support epilepsy diagnosis.

Abstract

Abstract

Abstract
The clinical relevance of pulse wave velocity (PWV), as an indicator of cardiac risk associated to arterial stiffness, has gained clinical relevance over the last years. Optic sensors are an attractive instrumental solution for this type of measurement due to their truly non-contact operation capability, which has the potential of an interference free measurement. The nature of the optically originated signals, however, poses new challenges to the designer, either at the probe design level as at the signal processing required to extract the timing information that yields PWV. In this work we describe the construction of two prototype optical probes and discuss their evaluation using three algorithms for pulse transit time (PTT) evaluation. Results, obtained in a dedicated test bench, that is also described, demonstrate the possibility of measuring pulse transit times as short as 1ms with less than 1% error. © Springer-Verlag Berlin Heidelberg 2013.

Abstract
Sub-millimetre distension waveforms (0.7 mm, max) are assessed using two new optical probes. The probes differ on the type of photo-detector used: planar photodiodes (PPD), in one case, and avalanche photodiodes (APD), in the other. Performance of the probes is evaluated in an especially developed test setup and in vivo, at the carotid site of humans. In the latter case, distension (associated to the pressure wave generated by the left ventricle contraction that propagates through the arterial system) carries clinically relevant information that can be extracted if, as will be shown, the waveforms are accurate and have enough resolution. An ultrasound image system, Vivid" e, was used as source of reference data for comparison. Along with the probes, a set of software routines was also developed to extract artefact-free data and evaluate the error. Results from the test setup demonstrate the possibility of waveform distension measurements with less than 6% error for both optical probes in this study. In comparison with an ultrasound system, the optical sensors allow the reproduction of the arterial waveform with a higher resolution, adequate to feed feature extraction algorithms.