PURPOSE To obtain a better understanding of oxygen and nutrient transport within the lens, the viscosity of whole lenses was investigated using a fiber optic oxygen sensor (optode). The diffusion coefficient of oxygen was calculated using the Stokes-Einstein equation at the slip boundary condition. METHODS The optode was used to measure the oxygen decay signal in samples consisting of differe...

The time response behavior of Aanderaa optodes model 3830, 4330, and 4330F, as well as a Sea-Bird SBE63 optode and a JFE Alec Co. Rinko dissolved oxygen sensor was analyzed both in the laboratory and in the field. The main factor for the time response is the dynamic regime, i.e., the water flow around the sensor that influences the boundary layer’s dynamics. Response times can be drastically re...

The aquatic eddy covariance technique is increasingly used to determine oxygen (O2) fluxes over benthic ecosystems. uses O2 measuring systems that have a high temporal and numerical resolution. In this study, we performed series of lab field tests assess new optical submersible meter designed for measurements equipped with an existing ultra-high speed fiber sensor. has 16-bit digital-to-analog-...

Cerebral vasomotion was studied on the human brain in vivo by use of multi-optode frequency domain near-infrared spectroscopy (NIRS). Vasomotion is a spontaneous oscillation with a frequency of 0.1Hz in the arterial flow. We investigated (1) the fluctuations of cerebral hemodynamics on the dynamical characteristics of cerebral vasomotion and (2) the dynamical coupling between vasomotion in the ...

We report on the first three-dimensional, volumetric, tomographic localization of vascular reactivity in the brain. To this end we developed a model-based iterative image reconstruction scheme that employs adjoint differentiation methods to minimize the difference between measured and predicted data. The necessary human-head geometry and optode locations were determined with a photogrammetric m...

A novel approach is presented for computing optode placements that are adapted to specific geometries and tissue characteristics, e.g., in optical tomography and photodynamic cancer therapy. The method is based on optimal control techniques together with a sparsity-promoting penalty that favors pointwise solutions, yielding both locations and magnitudes of light sources. In contrast to current ...

We report here for the first time on a reversible photodynamic bulk optode sensor based on the photoswitching of a spiropyran derivative (Sp). The photoswitching of Sp induces a large basicity increase in the polymeric phase, which triggers the extraction of Cl(-) and H(+). Cl(-) is stabilized by a lipophilic chloride-selective ionophore inside the membrane, while H(+) binds with the open form ...