For a new product, one of its features will be to measure the heart beat rate. I know of a methode using red/IR-LED to light through your finger and then measure the change in intensity as blood pass by, but I cant find any good resource describing these methodes or others. Anyone knowing of anything??
Do you need theory or practical info like schematics, etc.? because some time ago I did a HB monitor with plethysmography (IR light). And I can help you with some info.
Theory and Schematics would do fine and an short description of your schematics.
By the way, I thought plethysmography utilized ultrasound to measure both systolic and diastolic blood preasure and not the beat rate (puls) of hart?
Second by the way... You seem to be an relaxed person
Hi,
Actually I am doing a non invasive continuous arterial pressure monitor not like 120/80, but as beat to beat (getting the pressure wave) as thesis project for my master grade, and that is right, plethysmography is used to measure the blood pressure but with IR light technique.
This is the scheme that I recommend you to get a good signal, the picture is not good looking because it was taken with mi cellphone, but it is quite simple. You can adjust the two potentiometers to put the signal between the 0-5v range for an ADC and to do the algorithm that detects every peak, or you can implement a window comparator with another op-amp or bjt transistor, this reduces software to only measure time between events.
Hope this will help
Although they use RF tuning amplifier, from my experience this method has poor results and noise sensitivity, the better way is to use analog multiplier for Doppler detecting
I guess you can try to implement pwm modulation of the led and synchronous reception at photosensor side. Experiment with duty cycle to achieve best combination of power consumption and sensitivity constraints .
...try to implement pwm modulation of the led and synchronous reception at photosensor side. Experiment with duty cycle to achieve best combination of power consumption and sensitivity constraints .
This would my idea too, then the most sensitive detection means sinchron switced with your sender
Trough PWM modus (or simpler adjusted/changed LED-pulsewidth) you can find a minimum pulslength what your electronics need to function, & so short is ilghtning as possible= saves battery power...
If you apply spetial wavelength of light: maybe you can be more sensitive to blud!
Do you need theory or practical info like schematics, etc.? because some time ago I did a HB monitor with plethysmography (IR light). And I can help you with some info.
hello narccizzo
my final year project is also related to heart beat monitoring
can u give detailed info about your project(Heart beat monitoring)
I'hv need it