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Angular Piezo Actuator Controlled Laser Resonator for Precise Sensing of Respiratory Diseases
* 1 , 2 , 3
1  Department of Electronics & Telecommunication, University of Mumbai, Mumbai
2  Veermata Jeejabai Technological Institute, Mumbai, India
3  Faculty of Engineering, Hokkaido University, Sapporo, Japan


Breath analysis is a powerful noninvasive technique for diagnosis and monitoring of respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD). Nitric oxide (NO), nitrous oxide (N2O), carbon dioxide (CO2) and carbon monoxide (CO) are markers of airway inflammation and can indicate the extent of respiratory diseases. A system is proposed to design and develop table top Breath Analyzer instrument. Its subsystems consist of a compact fast response laser system for analysis of multiple gases by infrared absorption. For quantitative analysis of trace gases in human breath, patient’s breath sample is collected inside a gas chamber. Two ends of gas chamber are mounted with concave mirrors with special type of mirror holders which have two angle adjustment piezo actuators. Angle adjustment piezo actuators are used to compensate for any angular misalignment in order of micro radians. Third piezo actuator is used for expansion of laser resonator. Special mirror holder consists of three plates which are supported with guide pins. Mirror is mounted on tilt plate which can be rotated in vertical and horizontal direction with the help of two piezo actuators. This mirror holder structure is made of stainless steel and can be used in any type of air and vacuum environment. When NO, CO, carbon dioxide (CO2) and nitrous oxide (N2O) in exhaled breath of test subject interacts with IR laser absorption of laser occurs and transmitted light intensity reduces. This change in intensity is detected at photo diode and feedback to piezo actuator for stabilization of whole system.  The breath analysis system can be demonstrated and deployed in a preliminary study of volunteers in a trial clinical study.