Table 1.

Differences in an architecture, basic components, and mechanical realizations of all three PPG sensor prototypes.

Sensor Prototype	Optical Sensor Part	Mounting Method	Wearable	Arduino Board (1)	BT Module/Standard	Sensor’s Body Dimensions (L × W × H)	Sensor’s Body Weight
PPG-EP	HRM-2511E	rubber ring	No	Uno v. 3.0	HC-06/BT 2.0	105 × 70 × 80 mm	445 g
PPG-PS1	Adafruit 1093	1” aluminum target fixed by elastic ribbon	Yes	Nano v. 3.0	HC-06/BT 2.0	80 × 20 × 10 mm	38 g
PPG-BLE	Adafruit 1093		Yes	Pro Mini v. 2.0	MLT-BT05/BT4.1 BLE	40 × 25 × 15 mm	40 g (2)

⁽¹⁾ All Arduino boards are based on the processor ATmega328 with 10-bit A/D converters; ⁽²⁾ Including mounted Li-Po battery cell.