Simulation for pulse oximeter

Abstract

A method and system for simulating living tissue which is to be monitored by a pulse oximeter that provides red and infrared light flashes, the system including structure for: converting the red and infrared light flashes of the pulse oximeter into electrical signals; modulating the converted electrical signals to provide modulated electrical signals; and converting the modulated electrical signals to light flashes and transmitting the converted light flashes to the pulse oximeter for detection so that the pulse oximeter responds to the converted light flashes as it would to light flashes modulated by a living tissue.

1. A method for simulating living tissue which is to be monitored by a pulse oximeter that provides red and infrared light flashes, the method comprising:
 a. converting the red and infrared light flashes of the pulse oximeter into electrical signals;  
 b. modulating the converted electrical signals to provide modulated electrical signals; and  
 c. converting the modulated electrical signals to light flashes and transmitting the converted light flashes to the pulse oximeter for detection so that the pulse oximeter responds to the converted light flashes as it would to light flashes modulated by a living tissue.  
 
     
     
       2. The method as defined in  claim 1 , further comprising the step of blocking the red and infrared light flashes produced by the oximeter from being directly detected by the pulse oximeter. 
     
     
       3. The method as defined in  claim 1 , further comprising the steps of:
 converting the brightness of each light flash created in step (c) into a proportional electrical signal;  
 comparing said proportional electrical signal to the amplitude of the modulated electrical signal formed in step (b); and  
 adjusting the light intensity of the light flash formed in step (c) so as to null out any difference between said proportional electrical signal and said modulated electrical signal.  
 
     
     
       4. An apparatus for simulating living tissue which is to be monitored by a pulse oximeter that provides red and infrared light flashes, the apparatus comprising:
 first means for converting the red and infrared light flashes of the pulse oximeter into electrical signals;  
 second means for modulating the converted electrical signals to provide modulated electrical signals; and  
 third means for converting the modulated electrical signal to light flashes and transmitting the converted light flashes to the pulse oximeter for detection so that the pulse oximeter responds to the converted light flashes as it would to light flashes modulated by a living tissue.  
 
     
     
       5. The apparatus as defined in  claim 4 , further comprising means for blocking the red and infrared light flashes produced by the oximeter from being directly detected by the pulse oximeter. 
     
     
       6. The apparatus as defined in  claim 4 , further comprising:
 means for converting the brightness of each light flash created by said first means into a proportional electrical signal;  
 means for comparing said proportional electrical signal to the amplitude of the modulated electrical signal formed by said second means; and  
 means for adjusting the light intensity of the light flash formed in said third means so as to null out any difference between said proportional electrical signal and said modulated electrical signal.  
 
     
     
       7. The system of  claim 4 , wherein the means for converting the red and infrared light flashes of the pulse oximeter into electrical signals comprises photodiode detector means, amplification means, signal coupling means which removes the dc component from the amplified photodiode electrical signal, and dc restorer means to reference said photodiode electrical signal to a fixed level, regardless of photodiode output due to ambient light. 
     
     
       8. The system of  claim 4 , wherein said modulating means for modulating said electrical signals comprises a plurality of multipliers.