Design engineers working on wearables should take note of the new MAX30102.
This fully-integrated sensor module can perform pulse oximetry (i.e., monitor a person’s blood oxygen level) as well as heart rate when placed against the skin.
How Blood Oxygen Levels Are Measured
Blood oxygen levels in healthy humans should normally span between 95 and 99 percent loading of the hemoglobin found in arterial blood; that's the blood moving out from the heart and lungs. Making this measurement requires a lot of detailed information.
A typical oxymeter.
One other key issue is that these measurements need to made only for the arterial blood, which carries the maximally oxygenated hemoglobin, and not the venous oxygen-depleted blood.
Fortunately, the arterial blood always pulsates, as it's coming directly from the beating heart. This is why the technique is called pulse oximetry, as the system needs to see the pulse to know it’s measuring arterial blood.
Features of the MAX30102 Pulse Ox and Heart Rate Sensor
Some vital statistics of this new sensor are its:
- Ultra-low power consumption: running on 1.8V logic power and 5V only for driving the integrated LEDs
- Small solution size: being a 14-pin optical module (5.6mm x 3.3mm x 1.55mm) which integrates LEDs, photodetectors, integrated glass optics, and low-noise electronics
- Temperature Range: -40 to +85°C (-40 to +185°F)
A unique feature of this sensor is that it doesn't need to shine clear through a finger or earlobe, it can operate against a wrist, like a watch. This is a reflective solution.
This MAX30102 communicates through a standard I2C interface and can be dropped to a shutdown power of 0.7uA to help with battery life. It also allows programmable sample rates for dynamic energy savings.
MAXIM has also created a useful evaluation board to help with development needs. It includes an accelerometer for potential fitness applications.
They've even worked out a robust Motion Artifact Resilience ability. Motion artifacts are errors in readings caused by blood flow changes not related to pulse but rather from muscle use, like swinging an arm or adjusting a grip.
With 26 million smart garments estimated to ship this year , 2016 looks to be a banner year for wearables. Being able to add oximetry into step counters and other fitness-oriented devices gives users access to a host of new and vital information about their health.
If you're interested in the MAX30102 and looking for the details, register with MAXIM-IC on their website so you can fulfill their NDA requirements and secure a full data sheet.
Check it out here .