Optical sensor path selection

Abstract

A device includes a sensor for measuring a parameter for tissue. The sensor includes a plurality of optical elements including a plurality of detectors and at least one emitter. Separation distances between the various optical elements are selected based on a depth corresponding to a region of interest in the tissue and based on a depth corresponding to an exclusion region in the tissue.

1 . (canceled) 
     
     
         2 . A method comprising:
 identifying a region of interest disposed in a first layer of a biological tissue;   identifying an exclusion region disposed in a second layer of the biological tissue, the first layer exclusive of the second layer and the first layer having a greater depth than the second layer;   selecting a first depth corresponding to the region of interest;   selecting a second depth corresponding to the exclusion region;   using the first depth to determine a first dimension between a first emitter and a second detector and between a second emitter and a first detector, the first detector configured to generate a first output and the second detector configured to generate a second output;   using the second depth to determine a second dimension between the first emitter and the first detector and between the second emitter and the second detector;   using the first dimension to position the first emitter relative to the second detector in a housing of a sensor and to position the second emitter relative to the first detector in the housing; and   using the second dimension to position the first emitter relative to the first detector and to position the second emitter relative to the second detector in the housing, the sensor configured to determine a physiological parameter of the biological tissue.   
     
     
         3 . The method of  claim 2  wherein selecting the first dimension includes selecting approximately 40 mm. 
     
     
         4 . The method of  claim 2  wherein selecting the second dimension includes selecting approximately 20 mm. 
     
     
         5 . The method of  claim 2  wherein selecting the first dimension includes selecting approximately 25 mm. 
     
     
         6 . The method of  claim 2  wherein selecting the second dimension includes selecting approximately 12.5 mm. 
     
     
         7 . The method of  claim 2  further including configuring the housing for attachment to a forehead of a patient. 
     
     
         8 . The method of  claim 2  wherein the housing is configured for affixation proximate the skull. 
     
     
         9 . The method of  claim 2  wherein the first detector and the second detector are configured to provide a measurement signal corresponding to cerebral oximetry. 
     
     
         10 . The method of  claim 2  wherein the first dimension and the second dimension are configured to provide a measurement signal corresponding to cerebral oximetry for a neonate. 
     
     
         11 . The method of  claim 2  wherein the first emitter and the second emitter are configured to emit light at a selected wavelength. 
     
     
         12 . The method of  claim 2  further including coupling a processor to the first detector, the second detector, the first emitter, and the second emitter. 
     
     
         13 . The method of  claim 12  further including configuring the processor to determine tissue oximetry. 
     
     
         14 . The method of  claim 12  further including configuring the processor to provide an output signal corresponding to metabolites in the region of interest. 
     
     
         15 . The method of  claim 12  further including configuring the processor to sequentially power and un-power the first emitter and the second emitter. 
     
     
         16 . The method of  claim 12  further including configuring the processor to selectively activate the first emitter, the second emitter, the first detector, and the second detector. 
     
     
         17 . The method of  claim 12  further including configuring the processor to determine a physiological parameter based on addition and subtraction of signals from the detectors. 
     
     
         18 . The method of  claim 12  further including configuring the processor to determine an output signal in which optical absorbance corresponding to a short path is subtracted from optical absorbance corresponding to a long path.