Health-care sensors deliver low power, small size for wearables

By Gina Roos, editor-in-chief

Maxim Integrated rolls out two new health-care sensors designed to lower power consumption and reduce solution size for wearable health and fitness applications while improving sensor accuracy for measuring vital signs such as temperature, heart rate, and blood-oxygen saturation (SpO₂ ). The MAX30208 clinical-grade digital temperature sensor can reduce temperature measurement power by 50%, while the MAXM86161  integrated optical module for heart rate and SpO₂ measurement can shrink optical solution size by 40%. Designers can also improve sensitivity and accuracy with the highest signal-to-noise ratio (SNR) using the MAXM86161, said Maxim.

Claimed as the industry’s smallest fully integrated solution for heart-rate and SpO₂  measurements for hearables and other wearable applications, the MAXM86161 in-ear heart-rate monitor and pulse oximeter cuts package size by 40% compared to its closest competitor. It’s housed in a 2.9 × 4.3 × 1.4-mm OLGA package.

The MAXM86161 also touts best-in-class SNR, offering a 3-dB improvement with band-limiting signal for PPG use cases compared to the closest competitor. (Nyquist SNR is 89 dB; 100-dB SNR with averaging). It also offers about 35% lower power to extend battery life, with less than 10-μA operating power (typical at 25 sps) and 1.6 μA in shutdown mode, and cuts component count thanks to an integrated analog front end (AFE).

The MAX30208 offers temperature measurement accuracy of ±0.1°C in the range of 30°C to 50°C with a fast response time to changes in temperature and eliminates thermal self-heating. The MAX30208 consumes only half the power — 67-μA operating current during active conversion versus 135 μA.

The MAX30208 is compatible with up to four I² C addresses to enable multiple sensors on the same IC bus and can be attached to either a PCB or a flex printed circuit (FPC). The sensor is available in a 10-pin thin LGA package (2 × 2 × 0.75 mm). It can be used in small, battery-powered applications, including smartwatches and medical patches.

Available to purchase at Maxim’s website, the MAXM86161 and the MAX30208 are priced at $4.41 and $1.25, respectively, (1,000-up, FOB USA). They are also available from authorized distributors. Evaluation kits are available — the MAXM86161EVSYS#  evaluation kit is priced at $150 and the MAX30208EVSYS#  evaluation kit is available for $56.