Medical uses for comparator circuit?

Question

What are some of the uses in the medical field that a comparator using an op amp can provide?

Answer 1

Those blood oxygen monitors -- where they clamp a thing on your finger and a bright red light shines onto the finger -- use Op Amps as comparators to sense when the reflected light reaches a certain threshold.  There are actually 2 lights: red and infared with 2 detectors and 2 different comparator circuits.  It is the time-difference between when the 2 comparators switch that is the measure of blood oxygen %.

Pulse-rate monitors use the same principle.  A light is shined onto the finger and the reflection comes back strong/weak/strong/weak with the pulse.  A comparator senses when those transistions from strong reflection to weak reflection occur and sends that information to a counter/timer circuit which measures pulse rate.

.