Fig. 2.
Schematic diagram of the experimental arrangement used for evaluating the response time of particulate EPR oximetry probes. A function generator was used to drive a speaker to which a short plastic piston was attached. A diaphragm at one end of a T-tube was in contact with the piston. One arm of the T-tube contained the EPR probe while the other end was connected to a pressure sensor. A digital oscilloscope was used to acquire and display data collected by the pressure sensor. The vibration of the speaker cone resulted in a periodic spatial displacement of the diaphragm, changing the chamber volume and hence the pressure. The setup was capable of generating rapid oscillations (up to 300 Hz) in pO2.