pH change in tissue can be detected using infra-red light reflectance spectroscopy.
Severinghaus
J W
JW
D000818:Animals; D004567:Electrodes, Implanted; D006454:Hemoglobins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007511:Ischemia / Q000378:metabolism; D008991:Monitoring, Physiologic; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared
D006454:Hemoglobins; D010108:Oxyhemoglobins; D010100:Oxygen