Analog Devices has introduced a new electrochemical & impedance measurement front end that enables the next generation of vital sign monitoring devices and intelligent electrochemical sensors.
The AD5940 analog front end incorporates both potentiostat and electrochemical impedance spectroscopy (EIS) functionality on a single chip, allowing for sensor measurement in both time and frequency domains. The device features integrated hardware accelerators for advanced sensor diagnostics, best-in-class low noise for accurate sensor measurements and is designed for wearable “always-on” applications. Compared to traditional discrete solutions which pose limitations and require multiple ICs to achieve similar performance, ADI’s single chip solution offers advantages in terms of system accuracy and size flexibility to measure 2-Lead, 3-Lead and 4-Lead electrochemical sensors. It’s an ideal solution for applications, where high precision biological and chemical sensing is mission-critical, such as industrial gas sensing, liquid analysis, material sensing, vital signs monitoring, impedance spectroscopy and disease management.
The AD5940 is the lowest power, highest performance Impedance and electrochemical front end with intelligent autonomous control. The analog front end combines leading levels of integration and performance for potentiostat and impedance-based electrochemical sensor managements. The on-chip potentiostat allows for a host of standard electrochemical-based measurement techniques, such as amperometric, voltametric, or impedance measurements.
The AD5940 is designed to be used in healthcare-related bio-impedance systems for both skin impedance and body impedance measurements, and also to work with the AD8233 AFE in a complete bioelectric/biopotential measurement system.
AD5940 Functional Block Diagram
The analog front end chip can measure Voltage, current and impedance. The device consists of two potentiostat loops, a low bandwidth loop with ability to generate AC signals up to 200 Hz and a high bandwidth loop with ability to generate AC signals up to 200kHz. The ultra-low power Potentiostat consumes 6.5uA in biased mode.
The AD5940 measurement channel features a 16-bit, 800 kSPS, multichannel successive approximation register (SAR) analog-to-digital converter (ADC) with input buffers, a built in anti-alias filter (AAF), and a programmable gain amplifier (PGA). The ADC features an input voltage range of ±1.35 V. An input mux before the ADC allows the user to select an input channel for measurement. These input channels include multiple external current and voltage inputs, and internal voltage channels. The internal channels enable on chip diagnostic measurements of the internal supply voltages, die temperature, and reference voltages.
The AD5940 measurement blocks can be controlled via direct register writes through the Serial Peripheral Interface (SPI) interface, or alternatively, by using a pre-programmable sequencer, which provides autonomous control of the AFE chip. 6 kB of static random access memory (SRAM) is partitioned for a deep data first in, first out (FIFO) and command memory. Measurement commands are stored in the command memory and measurement results are stored in the data FIFO. A number of FIFO related interrupts are available to indicate state of the FIFO.
Click below to see the AD5940 capabilities when used to collect human vital signs
The AD5940 is very well supported with a choice of 2 different evaluation boards to help design engineers:
The EVAL-AD5940BIOZ evaluation board is designed for bio-impedance applications including Body Impedance Analysis (BIA) and Electrodermal Activity (EDA). This evaluation kit includes the EVAL-ADICUP3029 Arm® Cortex™-M3 microcontroller based Arduino Uno form factor board, the EVAL-AD5940BIOZ which contains the AD5940 for bio-impedance and the AD8233 for ECG measurements and also custom micro USB - ECG snap connectors.
The EVAL-AD5940ELCZ evaluation board is designed for high precision analysis of electrochemical cells. This evaluation kit is designed to easily configure the AD5940 to perform electrochemical measurements on a typical electrochemical cell. The evaluation kit includes the EVAL-ADICUP3029 Arm® Cortex™-M3 microcontroller based Arduino Uno form factor board, the EVAL-AD5940ELCZ daughter board and custom micro USB to crocodile cables to connect the hardware to various chemistry setups.
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Click here to download the datasheet for AD5940
Anglia are offering customers a FREE evaluation board and samples of the AD5940 Impedance & Potentiostat Analog Front End for Biological & Chemical Sensing from Analog Devices, please fill in the form below to register for your FREE samples now.
FREE samples for UK and Ireland customers only, subject to availability.
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