System and method for mainstream exhaled oxygen sensor
AssigneeThe Trustees of Princeton University
InventorsCharles L. Patrick, Jonas Westberg, Gerard Wysocki
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Abstract
According to various embodiments, a sensing device for measuring oxygen concentration cycles in breath is disclosed. The sensing device includes a laser configured to emit light at an A-band of oxygen, a lens configured to collimate the light, and a multi-pass cell configured to contain a replaceable sample cell. The light passes through the multi-pass cell and is attenuated by oxygen in the sample cell. The sensing device further includes a photodetector configurated to convert the attenuated light into an electrical signal, and a lock-in amplifier or an equivalent processing circuit configured to determine oxygen concentration from the electrical signal.
Claims10
A sensing device for measuring oxygen concentration cycles in breath, comprising:
- a laser configured to emit light at an A-band of oxygen;
- a lens configured to collimate the light;
- a multi-pass cell configured to contain a replaceable sample cell, wherein the light passes through the multi-pass cell and is attenuated by oxygen in the replaceable sample cell, the replaceable sample cell comprising a first window between the lens and multi-pass cell and a second window between the multi-pass cell and photodetector;
- a photodetector configured to convert the attenuated light into an electrical signal;
- and a lock-in amplifier configured to determine oxygen concentration from a ratio of 1st and 2nd harmonic signal values of the electrical signal, where the lock-in amplifier is further configured to determine a 3rd harmonic signal value that determines a center of oxygen transition for locking a frequency of the laser to the center of the oxygen transition.
Dependencies are inferred from the claim text.