Tag Archives: PPG


Using Easy Pulse mikro with MPLAB Xpress board

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Easy Pulse mikro is our new educational pulse sensor in a mikroBus form factor. Like our previous Easy Pulse sensors (Easy Pulse and Easy Pulse Plugin), it is also based on the principle of transmittance photoplethysmography (PPG) applied to a fingertip. The sensor consists of a pair of IR LED and photodiode to detect the cardiovascular pulse signal from the fingertip. The output of the sensor is passed through a necessary instrumentation amplifier to derive a nice and clean analog PPG waveform. The analog output is routed to the AN pin of the mikroBus connector. In this article, I will describe how to use the Easy Pulse mikro sensor with Microchip’s latest MPLAB Xpress development board for uniform ADC sampling of the analog PPG signal and sending the samples to a PC for post digital processing in order to retrieve the heart-beat rate. Currently, you can buy this sensor from our Tindie Store in United States and Elecrow Store in China.

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Easy Pulse mikro

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Easy Pulse Sensor (Version 1.1) Overview (Part 2)

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In Part 1 of this article, we briefly discussed about the principle of Photoplethysmography (PPG) and its applications in retrieving vital information about the cardiovascular system. The Easy Pulse sensor allows you to measure the pulse rate from fingertip using the transmission mode PPG. The Easy Pulse Version 1.1 uses the HRM-2511-E sensor that fits comfortably onto fingertip. Inside the sensor there is an IR LED that illuminates the finger from one side. A photodetector placed on the opposite side and facing towards the IR LED detects the transmitted light through the finger. The little variations in the transmitted light intensity are synchronous with blood volume changes and hence with the pumping action of the heart. The on-board electronics filters out the noise from the PPG signal and amplifies the signal so that it is readable by a microcontroller. In this part, we continue our discussion of Easy Pulse Version 1.1 and analyze the output signals at various stages of instrumentation.

Easy Pulse sensor (Version 1.1)

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Easy Pulse Sensor (Version 1.1) Overview (Part 1)

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The Easy Pulse sensor is designed for hobby and educational applications to illustrate the principle of photoplethysmography (PPG) as a non-invasive optical technique for detecting cardio-vascular pulse wave from a fingertip. It uses an infrared light source to illuminate the finger on one side, and a photodetector placed on the other side measures the small variations in the transmitted light intensity. The variations in the photodetector signal are related to changes in blood volume inside the tissue. The signal is filtered and amplified to obtain a nice and clean PPG waveform, which is synchronous with the heart beat. The original version of Easy Pulse uses the TCRT1000 reflective optical sensor to sense the blood variation in the finger tissue and outputs a digital pulse which is synchronous with the heart beat. Today, we are pleased to announce the release of Easy Pulse Version 1.1, which has some improvements over the original design. The new version provides both analog PPG waveform as well as digital pulse signal as separate outputs. Easy Pulse Version 1.1 board is available for purchase on Tindie. Recently, our Chinese distributor Elecrow has also started selling it for $18.50, and they can ship it world-wide at lower cost.

Easy Pulse version 1.1

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