Help needed to amplify AC 2 mv 1-3 Hz signal to 0-5 volts range.

[Eeshan Mishra]

I am designing a PPG SENSOR for heart rate calculation through AVR microcontroller.

I have read many circuits but all are flawed and have tested their filters in simulators

Can anyone suggest me a feasible bandpass filter that can give a gain of >100 and have cutoff frequency in the range 1-3 Hz.

OR

tell me about any amplifier ckt that can amplify 2-3 mv AC 1-3 Hz signal to 0-5 V AC signal.

please help me!!!
I really need it for my project.
THANKS IN ADVANCE

 

[code_slave]

Take a look at texas instruments, they have a range of chips specifically designed for this.

here is a start

https://www.ti.com/ww/en/analog/afe...P=corp_gmd_afe4400_tw&HQS=gmd-afe4400-bthi-tw

Maybe a bit more integration at the front end than you were looking for, but makes the back end way more manageable.

also go dig out 'Elector', every few months there is some design…..
https://www.diagram.com.ua/english/library/elektor-electronics-magazine/

 

[BradtheRad]

cutoff frequency in the range 1-3 Hz

Although this is in the range of pulse rates, the heartbeat sound itself is in the area of 10 Hz.

Heartbeat monitor projects (including bandpass amplifiers) have been the topic of several threads here.

Try a search on related words such as heart, heartbeat, etc. 'Pulse rate' maybe.

 

[D.A.(Tony)Stewart]

BPM can drop well below 1 Hz and spectral, energy density < 1Hz may indicate different medical conditions,

If this is just for counting purposes and not analytical, then it wont matter as long as your filter matches the spectral density for high pass * low pass for best SNR. e.g. 50~250Hz with notch for AC Hum

 

[Audioguru]

I fixed an electronic stethoscope project then tried it. My hearbeat was about 60 times per minute but my heartbeat sounded like Ka-BOOM, Ka-BOOM, Ka-BOOM etc. at a frequency of about 16Hz. What was vibrating at 16Hz??
My electret mic has no resonance and the flexible housing it was mounted in has no resonance. The volume of the mic housing was small so if it was resonant it would be at a high frequency. Maybe the skin on my chest and beneath the mic housing was vibrated at 16Hz by each heartbeat??

But PPG is optical sensing of blood volume or color changes in a blood vessel caused by heartbeats.

I recently had a medical test and a PPG sensor was placed on my finger. I heard the machine make a beat with each heartbeat BUT then a pause without a beat fairly frequently. I was scared that my heart was failing then I heard the beats and pauses from other people in the clinic.
Why did it frequently miss a heartbeat??