Abstract: In a serum measurement device, an analyte concentration measurement apparatus facilitates sampling and analysis of analytes in body fluid and includes an implantable serum sampling catheter comprising a biocompatible tubing enclosing a vacuum release lumen and a serum lumen that are interconnected by a port. The serum lumen is separated from the sampling catheter exterior by a membrane barrier. The sampling catheter is configured for drawing a serum sample from a body fluid compartment by creation of suction in the serum lumen.

Abstract: A lactate concentration measurement apparatus comprising a housing enclosing a sample chamber configured for holding a body fluid sample and measurement photo-optics that generate light and monitor light intensity along a plurality of optical paths in the sample chamber. The apparatus further comprises a plurality of optical filters aligned in respective optical paths of the optical path plurality comprising at least a first optical filter with light absorption by lactate and water and a second optical filter with light absorption to water alone. A logic determines lactate concentration based on a ratio of intensities detected at a first detector in an optical path intersected by the first optical filter and detected at a second detector in an optical path intersected by the second optical filter.

Abstract: A method for measuring concentration of an analyte in body fluid comprises acquiring a body fluid sample, emitting light into the body fluid sample, and detecting emitted light intensity on a plurality of optical paths through the body fluid sample. A plurality of optical filters are arranged in respective optical paths of the optical path plurality comprising at least a first optical filter with light absorption by an analyte and water and a second optical filter with light absorption to water alone. Light intensity passed through the first optical filter and passed through the second optical filter is measured and analyte concentration is determined based on a ratio of intensities detected at a detector in an optical path intersected by the first optical filter and detected at a detector in an optical path intersected by the second optical filter.

Abstract: In a tissue sensor, a plurality of emitters are configured to emit narrowband light into biological tissue at a plurality of selected wavelengths including one or more wavelengths indicative of a profile for one or more selected analytes and a reference wavelength at which absorbance for the selected analyte is negligible. The sensor further comprises a photo detector configured to detect light at wavelengths that emerge from the biological tissue.

Abstract: Glucose concentration is noninvasively measured by measuring a plurality of absorption values using at least one emitter operating at a corresponding plurality of emission wavelengths through a common optical sample volume and deriving glucose concentration from the absorption measurement values.

Abstract: An optical sensor includes an optical source capable of being positioned on a tissue and emitting near infrared light into the tissue at a plurality of selected wavelengths, and a photodetector capable of detecting reflected light from the tissue. The photodetector being positioned on the tissue removed from the optical source but sufficiently close in proximity to the optical source to contact the same general tissue. The optical sensor further includes an oscillator coupled to the optical source and capable of activating the optical source to emit the near infrared light, and a modulator coupled to the oscillator and capable of controlling radio frequency modulation of the optical source to emit a radio frequency component that is used to measure the optical path length and absorbance of an analyte of interest within the tissue.

Abstract: A diagnostic apparatus includes a near infrared spectrophotometer (NIRS) and an ultrasound transducer that operate in combination to improve diagnostic measurements. The diagnostic apparatus includes a near infrared spectrophotometer that measures an analyte, for example tissue oxygenation, in an optical sample volume and an ultrasound imager to accurately position the optical sample volume in biological tissue or vessels. In one example, the diagnostic apparatus includes an optical source, a linear array of ultrasound transducers, and an optical photodetector arranged in the same plane so that the ultrasound sample volume interrogated by the ultrasound transducers intersects the optical sample volume formed by the optical source and detector.