RoadTest: MAX30001 EV Kit (ECG, BioZ, Heart Rate, and Pace)
Author: rthoelenuh
Creation date:
Evaluation Type: Semiconductors
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: The Texas Instruments ADS1292R can be used to measure ECG and respiration as well.
What were the biggest problems encountered?: We have been looking for the a method to extract the phase information of the recorded impedance value, but were unable to obtain this information. No programmer or source-code was provided, but it is quite easy to use your own microcontroller with the development board.
Detailed Review:
Introduction
First of all I would like to thank Maxim Semiconductor for the opportunity to take part in this road test. This board is very easy to get started with, all the relevant info can be obtained from the datasheet at the Max30001EVKit product page, after completing a swift registration. A quick-start guide for the provided windows software is included in the datasheet and gets everything up-and-running very fast.
Package contents and initial thoughts
MAX30001 Evaluation Board
MAX32630FTHR Pegasus rapid development platform
ECG Cables (3 are included)
Micro-USB Cable (Decent quality)
The evaluation board is of high quality and contains connectors for standard ECG-leads,which can be used for the impedance as well. No ECG patches were delivered with the kit, so you have to source them from elsewhere. The board is quite bulky at 14 x 9.8 cm (5.5 x 3.85 inch), and quite sparingly populated, especially when compared to the MaxRefDes100. Which was intended to carry the MAX30001 instead of the MAX30003/4 it is shipping with right now, as the documentation/source code is riddled with references to the former.
The MAX32630FTHR is a Cortex-M4F microcontroller board, running at 96 MHz. It is a branded "Pegasus" because it is compatible with Adafruit Feather development system and their Feather wings expansion boards. The boards are connected via default 0.1 inch pin-headers. No programmer is included in the package, but the firmware the device ships with works out-of-the-box with the supplied windows program. Power is applied to the evaluation board through the micro-usb connector of the MAX32630 board, data is exchanged over this connection as well.
Everything was packaged in a cardboard box and inside a static dissipative bag, the board itself was furthermore packaged inside a conductive silver coated bag.
Getting started with (Bio-)impedance
On my Window 10 x64 device, the driver for the MAX32630FTHR was detected and installed automatically as a virtual serial port. When you launch the windows software, you are greeted with a "Connection Issue" screen, after pressing "OK", you can enter the following Serial Port Settings: as found in the device manager ("Maxim EV Kit Serial Port (COM XX)").
The connect button brings up the main program. The "Home" tab has a selection of "Quick Start Settings" which configure the registers of the device for the selected task, these can be written by clicking the "Apply Settings". Data from the board can be viewed in real-time in the "plots" window by selecting the desired channel and starting the monitor. The operation of the BioZ channel can easily be verified by attaching a resistor (e.g. 10 kOhm) across the BIP and BIN terminals or by using the built-in 100 Ohm resistor{Settings of the oscillator have to be changed as described in the data sheet}.
Specific application
I have reviewed the MAX30001 with a specific application in mind: to measure the respiration rate via a chest strap with a home-built capacitive stretch sensor. This sensor is constructed as can be seen in the image below.
The device was set up using the following steps:
Step 1 :
You open the Bioz Channel tab and change the Analog HPF Cutoff from 1000Hz to Bypass like in the picture below.
Step 2:
After that you go to channel gain and change the 10v/v to 20v/v.
Step 3:
Go to Digital LPF Cutoff and change the 4Hz to Bypass.
Step 4:
Change the Current Generator Frequency from FMSTR/64(~500Hz) to FMSTR/8 (4Khz).
Step 5:
Change the Magnitude to 8µA.
Step 6:
Change Mode to Chopped w/ Resistive CM.
Step 7:
Check the BioZ down the window at Channel/Plot Enable.
Step 8:
Go to the Bioz MUX page and connect all the switches like in the picture below.
Step 9:
Go to Lead Bias and change the Resistive lead Bias enable from disabled to BioZ Ch.
Step 10:
Change the Resistive Bias value to 200MΩ.
Step 11:
Change the Neg. Input Bias Enable to Connected.
Step 12:
Go to plot and open the options tab and click on BioZ Miliohm Scale.
Step 13:
Click on the start Monitor.
you can clearly see my respiration pattern on the plot, however without the 50Hz Notch filter enabled, this signal is quite noisy. I connected my sensor to the BIP and the BIN terminals on the MAX30001 EVKIT. As can be seen in the picture below, the respiration was monitored breath around the waist.
A screen-captured video of the interface, with the 50Hz filter enabled can be seen in the video below:
The bio-impedance channel was able to record the capacitance change of the breathing belt very accurately. This change is directly proportional to circumference of the chest, and is not influenced by the change in temperature or relative humidity when compare to a purely resistive breathing belt. The Max30001 dev kit allows the measurement of an ECG simultaneously with the breathing pattern, but therefore the band has to be upgraded with dry ECG electrodes eg. additional conductive textile electrodes.