The wearable devices market is growing and so are the investments into the development of such devices. In order to satisfy the demands on wearable devices, such as being simple, ergonomic and low-power, it is necessary for experts in various fields to work together. An example of technology increasingly used in such devices is photoplethysmography (PPG). It is based on detecting changes in light passing through or reflecting off tissue. The photoplethysmograph in this paper is consisted of an analog channel with two different wavelengths (green light and infrared (IR) radiation) and two embedded systems. The photodiodes have peak sensibility at wavelenghts of 580nm and 900nm. The voltage at the output of the analog channel in range of 0-3V is sampled and converted into 10-bit digital value. The collected data is transferred using radiocommunication and UART serial communication to a laptop in order to present the data in a more convenient form - a curve. Using two wavelengths lays the groundwork for getting information about oxygen saturation. Solar energy is harvested and used to power one of the embedded systems. A great deal of attention is paid to minimising the size and power consumption. When operating with the green channel, maximum power consumption (at duty cycle 1/2) is 98,07mW, while the maximum IR channel consumption is 90,42mW. The photoplethysmograph in this paper is fully functional, but in order to be comparable to commercially available photoplethysmographs, improvements are necessary.