Body Composition, Hydration, Bioimpedance Analysis

The MAX86178 is a highly integrated, multiple vital-sign monitoring device with a complete photoplethysmogram (PPG), electrocardiogram (ECG) and biopotential (BioZ) analog front end (AFE) for wearable applications. The MAX86178 offers high performance for wellness and clinical applications with low power for long battery life.

The PPG data acquisition system supports up to 6 LEDs and 4 photodiode inputs. The LEDs are programmable from two high-current, 8-bit LED drivers. The receive path has two low-noise, high-resolution readout channels that each include independent 20-bit ADCs and industry-leading ambient light cancellation (ALC) circuits, producing the highest performing integrated optical data acquisition system on the market today.

The ECG channel has EMI filtering, internal lead biasing, right-leg drive, and extensive calibration voltages for built-in self-test. The ECG channel also has high-input impedance, low noise, high CMRR, programmable gain, an anti-aliasing low-pass filter, and a high-resolution ADC. It is designed to meet IEC 60601-2-47 Ambulatory ECG Systems monitoring compliance requirements.

The BioZ receive channel has EMI filtering and extensive calibration features. The BioZ receive channel also has high input impedance, low noise, programmable gain, low-pass and high-pass filter options, and a high-resolution ADC. There are several modes for generating input stimulus: balanced square-wave source/sink current, sine-wave current, and both sine-wave and square-wave voltage stimuli. A wide range of stimulus magnitudes and frequencies is available.

The MAX86178 has DC and AC lead-off detection, a flexible timing system, and a PLL. All three sensor channels are synchronized. The MAX86178 is available in a 7 x 7 49-bump wafer-level package (WLP) with package dimensions of 2.77mm x 2.57mm, and operates over -40°C to +85°C temperature range.

Applications

• Ambulatory Heart Monitors
• Impedance Cardiography/Hemodynamic Monitors
• Pulse Arrival Time (PAT), Pulse Travel Time (PTT), Pulse Wave Velocity (PWV) Assessments
• Pulse-Oximetry Devices
• Single- and Multi-Frequency Bioimpedance Analysis
• Smart-Clothing Applications
• Wearable Vital-Sign Monitors

The MAX30009 is a complete Bioimpedance (BioZ) Analog Front-End (AFE) solution for wearable applications. It offers high performance for fitness, wellness, and clinical applications, and ultra-low power for long battery life. The BioZ receive channel has Electrostatic Discharge (ESD) protection, Electromagnetic Interference (EMI) filtering, internal lead-biasing, DC leads-off detection, DRVN lead-off detection, and ultra-low power lead-on detection during standby mode. The BioZ receive channel also has high input impedance, low noise, high Common-Mode Rejection Ratio (CMRR), programmable gain, various low-pass and high-pass filter options, and two high resolution analog-to-digital converters for simultaneous I and Q acquisition.

The BioZ transmit channel has a sine-wave current generator to drive AC currents into the body with a wide frequency range of 16Hz to 806kHz and a wide magnitude range of 16nA_RMS to 1.28mA_RMS. The transmit channel can also operate in the sine-wave voltage and H-bridge modes. The flexible input/output MUX allows for both bipolar and tetrapolar measurements with multiple sets of electrodes.

For measurements requiring high absolute impedance accuracy such as Bioimpedance Analysis/Spectroscopy (BIA/BIS) and Automated External Defibrillator (AED) body impedance, the MAX30009 offers several calibration options. An external precision resistor can be connected to the four-wire calibration port for the highest accuracy. Internal trimmed resistors also provide high accuracy.

The PLL-based timing subsystem allows for a wide range of fine-tuned stimulus and sampling frequencies, and can be synchronized with other Analog Devices biosensors for simultaneous data collection.

The MAX30009 is available in a 2.03mm x 2.03mm, 25-bump Wafer-Level Package (WLP), operating over the -40°C to +85°C temperature range.

Applications

• Wearable Fitness, Wellness, and Medical Devices
• Multifrequency Body Composition Analyzers
• Non-Invasive Hemodynamic Monitors
• Automatic External Defibrillators
• Optimized Performance to Accurately Detect:
• Respiration Rate
• Galvanic Skin Response/Electrodermal Activity
• Bioimpedance Spectroscopy
• Body Composition and Fluid Analysis
• Impedance Cardiography and Plethysmography

The ADuCM350 is a configurable Impedance Converter and Potentiostat with current and voltage measurement capability for both Electrochemical sensors and Biosensors. It is a complete, coin cell powered, high precision, MCU integrated solution for portable device applications such as point-of-care diagnostics and body-worn devices for monitoring vital signs.

The ADuCM350 analog front end (AFE) features a 16-bit, precision, 160 kSPS analog-to-digital converter (ADC); 0.17% precision voltage reference; 12-bit, no missing codes digital-to-analog converter (DAC); and a reconfigurable ultralow leakage switch matrix. It has 4 voltage measurement channels, up to 8 current measurement channels and an impedance measurement DFT engine. The ADuCM350 also includes an ARM Cortex-M3-based processor, memory, and all I/O connectivity to support portable meters with display, USB communication, and active sensors. The ADuCM350 is available in a 120-lead, 8 mm × 8 mm CSP_BGA and operates from −40°C to +85°C.

To support extremely low dynamic and hibernate power management, the ADuCM350 provides a collection of power modes and features, such as dynamic and software controlled clock gating and power gating. The AFE is connected to the ARM Cortex-M3 via an advanced high performance bus (AHPB) slave interface on the advanced microcontroller bus architecture (AMBA) matrix, as well as direct memory access (DMA) and interrupt connections.

APPLICATIONS

• Point-of-care diagnostics
• Body-worn devices for monitoring vital signs
• Amperometric, voltametric, and impedometric measurements

The AD5933 is a high precision impedance converter system solution that combines an on-board frequency generator with a 12-bit, 1 MSPS, analog-to-digital converter (ADC). The frequency generator allows an external complex impedance to be excited with a known frequency. The response signal from the impedance is sampled by the on-board ADC and a discrete Fourier transform (DFT) is processed by an on-board DSP engine. The DFT algorithm returns a real (R) and imaginary (I) data-word at each output frequency.

Once calibrated, the magnitude of the impedance and relative phase of the impedance at each frequency point along the sweep is easily calculated. This is done off chip using the real and imaginary register contents, which can be read from the serial I²C interface.

The AD5934 is a high precision impedance converter system solution that combines an on-board frequency generator with a 12-bit, 250 kSPS, analog-to-digital converter (ADC). The frequency generator allows an external complex impedance to be excited with a known frequency. The response signal from the impedance is sampled by the on-board ADC and a discrete Fourier transform (DFT) is processed by an on-board DSP engine. The DFT algorithm returns a real (R) and imaginary (I) data-word at each output frequency.

Once calibrated, the magnitude of the impedance and relative phase of the impedance at each frequency point along the sweep is easily calculated using the following two equations:

A similar device, available from Analog Devices, Inc., is the AD5933, which is a 2.7 V to 5.5 V, 1 MSPS, 12-bit impedance converter, with an internal temperature sensor, available in a 16-lead SSOP.

Applications

• Electrochemical analysis 
• Bioelectrical impedance analysis
• Impedance spectroscopy 
• Complex impedance measurement
• Corrosion monitoring and protection equipment
• Biomedical and automotive sensors
• Proximity sensing
• Nondestructive testing 
• Material property analysis 
• Fuel/battery cell condition monitoring