The Heart Rate 7 Click Board™ is an optical biosensor Click Board™ that can be used for heart-rate monitoring (HRM). This Click Board™ employs a very sensitive analogue front-end IC with a high dynamic range, which ensures accurate and reliable readings. This analogue front-end IC is coupled with the optical front end, which consists of a sensitive photo-diode (PD) and two high brightness green LEDs. The photo-diode is the most sensitive to a visible light spectrum, offering reasonably high current output compared to other, standard type PD elements used so far, thus providing very accurate HRM readings.