Analog front end boosts sensor accuracy in wearable designs

By Majeed Ahmad, contributing writer

Analog Devices Inc. has released a new analog front end (AFE) that incorporates potentiostat and electrochemical impedance spectroscopy (EIS) functionality on a single chip to facilitate sensor measurement in both time and frequency domains. The on-chip potentiostat enables a host of standard electrochemical-based measurement techniques such as amperometric, voltametric, and impedance measurements.

Designed for biological and chemical sensing, the AD5940 chip has integrated hardware accelerators for advanced sensor diagnostics. It incorporates a low-noise feature that ensures accurate sensor measurements for always-on wearable applications. ADI is targeting its electrochemical and impedance measurement AFE chip at the next generation of vital-sign−monitoring devices and intelligent electrochemical sensors.

The applications that AD5940 can serve include industrial gas sensing, liquid analysis, material sensing, impedance spectroscopy, and disease management. It can also be used in health-care−related bio-impedance systems for both skin-impedance and body-impedance measurements.

Compared to traditional discrete solutions, the single-chip solution offers advantages in system accuracy and size flexibility to measure two-lead, three-lead and four-lead electrochemical sensors, said ADI.

The AFE chip can measure voltage, current, and impedance, and it’s available in a 3.6 × 4.2-mm, 56-ball WLCSP. Available in production volume, the AD5940 is priced at $4.17 for 1,000-unit quantities.