hello there,

I am kinda new to electronics and don't know much about them (so please excuse my ignorance) but i've to design a circuit and need some help; can some one please give me some ideas about how to get started?

I need to design a circuit that would monitor arterial CO2 levels (or end tidal CO2). The circuit must use the output from an infrared CO2 detector (i have this sensor the detects CO2), determine when exepirations occur, and detect the peak value of analog voltage corresponding to CO2 for each expiration. This peak should be held (i.e. results should be displayed on the oscilloscope etc.) until the next breath. Peaks from one breath to another may increase or decrease from previous values. So i need to design the circuit to detect expirations and hold the peak value until the next one is available.

I was thinking that I can take the output value from the infrared detector feed it to an Op Amp, then feed that signal to a schmitt trigger to, then to a set-reset flip-flop etc... along those lines.

Can someone please tell me what kind of components I may use to acomplish this task. Thank you.

 

Here's a block diagram of an analog implementation. You might be better off using a digital approach with a microcontroller or a DSP chip.

Attached Images

co2_pk.gif (7.8 KB, 157 views)