If the heartbeat is to be measured from the radial arteries of the wrist, we can implement pulse oximeter principle. There are two LEDs, i.e. red and infra-red LED. They emit different wavelength light, which are transmitted differently through the arteries. Now, ration of the two transmitted light o/p is equal to ratio of oxyhaemoglobin to deoxyhaemoglobin, which is present in the blood. Hence, from the light o/p, we can get a measure of the haemoglobins ratio, which in turn, in dependent on the pulse beat.

I knew about this but I can not use it because of optical noise and ..

I would suggest you to go for ECG analysis. What you can do is acquire the signal using ECG electrodes and process it in MATLAB or LabVIEW to filter and amplify as per requirement. Then find out the time period between R-R intervals. divide this by the sampling frequency. This will give you time period for 1 R-R interval. Multiply it by 60 to get Heart rate in beats/minutes. If you have any doubt feel free to message me.

Best Regards for your project.

Mr Parth Shah thanks

but I want to design a small and portable PCB Board does the processing of the signal real-time with DSP processor.

Best Regard.

Mr. Moradi,

Your question sounds like you wish to undertake invasive heart rate monitoring as opposed to non-invasive methods performed routinely by most modern blood pressure monitors you can purchase from pharmacies.  Perhaps if you state the purpose of your design then you might receive many more responses in addition to the very good ones you have had, all of which are suited for application in non-invasive monitoring.