The electrocardiograms are great to distinguish cardiac dysfunction from each other but are not suitable (or otherwise uncomfortable) to be used for research of arrhythmias.
Electrocardiograms and arrhythmias
As an ECG should be used twelve “derivations”. Each derivation displays the differential voltage between a pair of electrodes. They can serve ten electrodes, six positioned on the chest and four legs and arms. The preparation is complex, you have to clean the skin with alcohol, apply many wires and adhesive electrodes with a conductive paste.
The preparation takes several minutes, more almost as long to remove the electrodes and get dressed.
But arrhythmias need to be "caught in the act" and not many minutes after. Not even put the patient to bed, ECG offline for a few days can be enough because the arrhythmias are spiteful, may not occur for months, begin suddenly and last only a few minutes. They are real difficulties, so that the solution you get to implant a sensor under the skin, connected via radio to a control unit positioned near the bed (to home), and send the data via telephone to the national health system.
Differences between the ECG signals and OCG
To look the only arrhythmias given that interests us is the time that elapses between a pulse and the next. So comfortable you can use optical sensors that do not require preparation instead of classic sensors for ECG.
OCG (Optical Cardio Grapy) (Note 1) – I optical sensors They are convenient for frequent testing to be done at home and seize arrhythmias when they occur. The sensor and the special amplifier designed by us produce an almost constant signal varying also very patient characteristics (blood pressure, positioning of the sensor and thickness of the biological tissue). The similar sensors which are located in the network are instead influenced. With persons who have low blood pressure produce a signal so weak and disturbed as to render impossible the control of arrhythmias.
ECG (Electro Cardio Graphy) - The classics differential amplifiers for ECG who are more awkward to use (Note 2). These sensors require special electrodes with conductive paste and a skin preparation with alcohol and cotton. The preamplifier requires special components so it can not be built DIY. And even with all these treatments the system is very sensitive to movements, so you have to stand still to avoid disturbing the recordings.
(Note 1) The exact name for the optical detection would "photoplethysmography" but it's hard to remember and too poorly composed. Given that optical variations are detected instead of electrical, the equivalent of "Electro" is not "PhotoPlethysmo" but "Optical" and then we'll call OCG.
(Note 2) The only advantage of ECG sensors compared to optical ones you can see the electrical activity of the heart but to do this derivation is not enough, they must use twelve. They can serve ten electrodes, six positioned on the chest and four legs and arms. The preparation takes several minutes, more almost as long to remove the electrodes and get dressed. So this system is unsuitable for controlling arrhythmias. Arrhythmias require to be "caught in the act" and not many minutes after. Not even put the patient to bed, ECG wires connected for a few days can be enough because the arrhythmias are spiteful, may not occur for months and then begin suddenly and last a few minutes. They are real difficulties, so that the solution you get to be implanted under the skin a sensor connected via radio to a control unit positioned near the bed (to home) and send the data via telephone to the national health system.
The application Theremino ECG
This application displays and records the heart rate tracings. It is not a substitute for ECG viewers, but a specific application to highlight the variations in frequency and arrhythmias. Then it analyzes one lead and use two special graphics that are not present in the classic ECG. The first shows the frequency variations in time and the second shows the arrhythmias showing the correlation of the signal with itself shifted in time.
In thisvideo di YouTube you can see the application function. For more information on the application and to download a ZIP file that contains the entire project, including sources in Open Source, click this link.
You can also measure the saturation?
To measure the saturation serve two channel sensors, LED and phototransistor in different wavelengths. And the preamplifier would be more complex. To have a minimum accuracy of the mechanics of the LED position should be accurate and therefore the sensor would be difficult to build using traditional techniques. And finally, the calibration curve would be dependent on the mechanical construction. So you should have precision instruments and make a calibration by comparison.
For the saturation of blood there apparecchietti comfortable to put on the finger (to see This Page) costing less than nine euro on eBay shipping batteries included.
But these devices are not suitable for recording charts and explore them in time. Also they have a precision just enough and in many cases inadequate (even beyond the +/-3% error) while it is constructed in the best possible way. Copying them surely would get worse and then we would work a lot to get an accuracy so low as to be completely useless.
But we try arrhythmias, a task not covered by commercial equipment (both saturation meters that classic ECG). and we have therefore designed a particular sensor that is simple but which achieves maximum uniformity measurement, even with people who have very different characteristics.