Here I am, having fun with the MIO ALPHA heartrate sensor. During the Dutch Design Week in Eindhoven I had the opportunity to play with the MIO ALPHA for almost a week.
The first impression was very good. The rubber band was tightly fitting to the wrist, without feeling it (after a while). The measuring of the heartrate is done with light. There are 2 bright green leds which light up once you enable the measuring mode. The brightness of these leds depend on the ambient light which is being detected. Between the 2 leds I found a sensor (phototransistor) which is measuring the reflected amount of light. The sensor looks very similar to the BPW34, or might even be a BPW34. I am not sure about that one (yet).
There is a small bridge between the leds and the phototransistor, to prevent direct light from the led’s to reach the sensor.
I was able to connect to the heart rate sensor via Bluetooth Low Engergy (BLE). A couple of GATT UUID’s (Service: 6c721826-5bf1-4f64-9170-381c08ec57ee, Characteristics: 6c722a0a-5bf1-4f64-9170-381c08ec57ee and 6c722a0b-5bf1-4f64-9170-381c08ec57ee) which I do not know the feature of yet, but I am trying to find out what they do. I hope to get some help from MIO to get this sorted out.
To be continued . ..