Integrated sensor platform simplifies health and fitness design

November 01, 2016

steve.taranovich-November 01, 2016

Global wearable technology is a market worth $30B this year according to IDTechEx and is projected to grow by 9% over the next 3 years, but from 2019 that growth rate will jump almost exponentially to 23% into 2023 to $100B by 2023.

Circuit design engineers need to get product to market quickly but with tight time-constraints and a need to educate themselves regarding a myriad of new IC solutions emerging almost daily, it is a daunting task as best. There are so many IC solutions out there that need to be professionally designed into a working architecture that will serve customers who want to properly monitor their progress either in sports and fitness or their progress improving their health.

IC Manufacturers that produce helpful evaluation boards and reference designs in this area, who provide these welcome, professionally developed and tested tools that allow designers to evaluate a system design, are few and far between. Maxim Integrated happens to be one of the best in this area.

A newly released Health Sensor Platform, the MAXREFDES100#, is such a platform that takes the sheer volume of the many ICs that need to be properly integrated into a full architectural system and helps designers see and evaluate the features of these ICs at work in a fully functioning system architecture that will cut their design time down significantly. See Figure 1.

Figure 1: The MAXREFDES100# block diagram (Image courtesy of Maxim Integrated)

This so-called “hSensor” Platform will enable such things as measuring motion, precise skin temperature, and a multitude of biopotential measurements as well like electrocardiography (ECG), electromyography (EMG), and electroencephalography (EEG).

Another critical area of measurements that this system enables is reflective photo plethysmography measurements1 including pulse oximetry and heart-rate (HR) detection at three wavelengths, 880nm (infrared, IR), 660nm (red) and 537nm (green). Green light at 537 nm can be an excellent heart rate (HR) monitoring method during a normal everyday life activity because of its really good freedom from artifacts.

Red light is at a frequency where oxyhemoglobin and hemoglobin have identical absorbance. Using the difference between red and infra-red allows the concentration of oxyhemoglobin to be calculated.

Green light would be better in situations where Infrared light would interact with tendons, muscle and bone and create erroneous readings in a situation of high human activity.

A very low power, biopotential Analog Front End (AFE), the MAX30003, is at the heart of proper monitoring ECG and has a Heart rate detection algorithm consisting of a built-in piece of hardware to detect R-R intervals (the time between heart beats) using an adaptation of the Pan-Tompkins QRS detection algorithm2. See Figure 2.

Figure 2: The MAX30003 block diagram (Image courtesy of Maxim Integrated)

Continue to page 2 on Embedded's sister site, EDN: "What a circuit designer needs for a robust, wearable health sensor system design."


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