Comprising a complete integrated optical sensor module, a microcontroller sensor hub, and a sensing algorithm, the MAXREFDES220# optical blood-pressure trending solution can be embedded into smartphones or wearables. It enables users to place their finger on a device for 30 to 45 seconds while resting to measure blood pressure any where and any time.
"Blood pressure is a key vital sign, but has traditionally been difficult to monitor conveniently and accurately," says Kris Ardis, executive director in the Micros, Security and Software Business Unit at Maxim Integrated. "Maxim now provides a combination of products in a compact reference design which allows system designers to build highly accurate—and based on our patient testing, the most accurate—blood-pressure monitors that do not require cuffs."
The MAXREFDES220#, says the company, provides industry-best accuracy that meets Class-II regulatory limits. For example, under resting-only measurement conditions, the solution provides the following accuracies:
- Systolic Error: Mean = 1.7 mmHg, Std Dev = 7.4 mmHg
- Diastolic Error: Mean = 0.1 mmHg, Std Dev = 7.6 mmHg
- For reference, Class-II regulatory limits are |Mean Error| = 5 mmHg, and Std Dev = 8 mmHg
The solution requires calibration every four weeks to maintain the above accuracies. This is based on independent testing and a limited number of subjects at resting condition.
The reference design includes the MAX30101 or MAX30102 high-sensitivity optical sensor, as well as the MAX32664D sensor hub IC with built-in algorithms. The MAX30101 (using two LEDs) and MAX30102 (using three LEDs) pulse-oximeter and heart-rate optical sensor modules combine photodetectors, LEDs, and analog front-end (AFE) electronics with an integrated cover glass.
This integrated optical design and lenses-on-top approach, says the company, enables optimal signal-to-noise ratio (SNR) for a small, lower cost and power-efficient module. It comes in a 5.6 mm x 3.3 mm 14-pin optical package with an I2C interface to the sensor hub IC.
The MAX32664D sensor hub IC includes firmware that controls the sensor and executes