A bubble detector/direction sensor for detecting the presence of liquid and gas in a stream of liquid and gas segments flowing through an elongated transparent tube and for sensing the direction of flow of the stream. The sensor has first and second light sources, first and second input fiber optic bundles, and first and second collection fiber optic bundles. The first and second input fiber optic bundles couple the first and second light sources to first and second sides of the tube, respectively, so that light passes through the tube. When the tube is filled with liquid, the light passing therethrough from each light source passes through first and second predetermined regions. When the tube is filled with gas, the light passing therethrough passes outside of the predetermined regions. The first and second collection fiber optic bundles are coupled to the second and first sides of the tube, respectively, outside of the predetermined regions. A circuit is provided for producing signals indicating the presence of liquid in the tube, the presence of gas in the tube, and the direction of flow of liquid and gas through the tube based upon the light received by the first and second collection fiber optic bundles.

A method and apparatus for continuously monitoring and measuring the concentration of gases in a gas-containing liquid such as a transformer oil. The method and apparatus employ a passive gas extraction technique which comprises a high performance membrane material to extract dissolved gases from the oil, and an IR-based sensor to detect gases present. The passive gas extractor extracts dissolved gas from the gas-containing liquid, there being a known relationship between the concentration of a constituent gas in the extracted gas and the concentration of the constituent gas remaining dissolved in the gas-containing liquid. The gas sensor senses the concentration of a constituent gas in the extracted gas, in the presence of other constituent gases. The gas sensor comprises a sample chamber which receives the extracted gas, a non-dispersive infrared (IR) absorption sensing system which generates an electrical signal corresponding to the light absorption, at one or more specified IR wavelengths, of the extracted gas in the chamber, and an electrical output comprising the electrical signal generated by the non-dispersive IR absorption sensing system. A processor having receives the electrical signal corresponding to the light absorption, at the one or more specified IR wavelengths, of the extracted gas in the chamber, and computes the concentration of at least one gas constituent present in the extracted gas.

The present invention is intended as a means of diagnosing the presence of a gas bubble and incorporating the information into a feedback system for opto-acoustic thrombolysis. In opto-acoustic thrombolysis, pulsed laser radiation at ultrasonic frequencies is delivered intraluminally down an optical fiber and directed toward a thrombus or otherwise occluded vessel. Dissolution of the occlusion is therefore mediated through ultrasonic action of propagating pressure or shock waves. A vapor bubble in the fluid surrounding the occlusion may form as a result of laser irradiation. This vapor bubble may be used to directly disrupt the occlusion or as a means of producing a pressure wave. It is desirable to detect the formation and follow the lifetime of the vapor bubble. Knowledge of the bubble formation and lifetime yields critical information as to the maximum size of the bubble, density of the absorbed radiation, and properties of the absorbing material. This information can then be used in a feedback system to alter the irradiation conditions.

An air or gas bubble detection system detects the presence of liquid in intravenous (IV) tubing. By detecting the presence of liquid rather than gas, false alarms due to micro bubbles or small air gaps between the sensor and the tubing are avoided.

Systems and associated methods are provided for improving detection and measurement of elements in a medium, particularly the measurement of gaseous bubbles in liquid medium, such as blood injected into a patient's body. The systems include a radiation emitter to emit radiation for traversing through a medium, and an analyzer subsystem to receive and to analyze the traversed radiation for presence and/or absence of gaseous elements in the medium. The methods include receiving at least one collection of data corresponding to at least one emitted radiation traversed through a medium, analyzing said collection of data for at least one predetermined condition; and generating a response upon detection of at least one predetermined condition.