Make With Mouser IoT Design Contest - Baby Vital Monitor_01 Introduction


My design proposal is to develop a Vital Monitor for babies using the Analog Devices Inc. EVAL-ADPD4100Z-PPG Evaluation Board.
baby chest strap.jpg

This project work intends to try out the EVAL-ADPD4100Z-PPG Evaluation Board to be used to measure
  • SpO2 using PPG,
  • Heart rate with single LEAD ECG and
  • Dehydration using skin impedance.
The evaluation board will be used to design a wearable sensor which can be mounted on the chest of the baby.

An Arduino Nano IOT 33 or ESP 32 will be used to acquire the data and send it to cloud through Wi-Fi.

ADPD4100 Description:

It’s a complete Multimodal Sensor Front End, can be considered to be an all-rounder in biomedical sensor design. The AFE is based on Trans Impedance Amplifier [TIA].

It has capability of driving up to eight light emitting diodes (LEDs) at total 400mA peak current and measuring current inputs through eight separate channels. Twelve separate time slots can be utilized to measure parameters in a single sampling period. It has programmable sampling rate from 0.004 Hz to 9 kHz using internal oscillators.

AFE consists of transimpedance amplifier (TIA), band-pass filter (BPF), integrator (INT) and analog-to-digital converter (ADC) stages. Dual-channel processing provides simultaneous sampling of two different parameters or a single differential signal.

A selectable second- to fourth-order cascaded integrator comb (CIC) filter provides on chip digital filtering.

The evaluation board is populated with ADPD4100 which supports SPI interface and operates @ 1.8v [analog core] and 1.8v / 3.3v [digital I/O].


** EVAL-ADPDUCZ microcontroller board is suggested by Analog Devices Inc. in the EVAL-ADPD4100Z-PPG product page, which can be used with the Wavetool Evaluation Software graphical user interface (GUI) that provides users with low level register access and high level system configurability. If I could get the EVAL-ADPDUCZ microcontroller board, that would reduce the development time period. Unfortunately [or may be actually fortunately!!], now I have to work from scratch – which is time consuming but I am enjoying the learning curve.

Modes of Operation:

The following layouts show the potential modes of operation for measuring SpO2, ECG and Impedance –


spo2 configuration layout.jpg

Figure: Basic PPG circuitry, SpO2 measurement needs two of it

ECG configuration layout.jpg

Figure: configuration of single LEAD ECG

Impedance: can be used for dehydration and respiration rate measurement

combined ECG respiration layout.jpg

Figure: Combined ECG and Respiration Rate measurement configuration
Source: Multiparameter Vital Signs Monitoring Is Easier Than Ever Before by Electronics Maker
November 21, 2020

**I could not complete the project within the time limit. However, working with the ADPD4100 evaluation board from scratch seemed to be very challenging and time consuming. I am still working on setting the configuration registers. Therefore, I am presenting my project scopes in this blog. I’ll keep posting updates on my progress from time to time.

In my next blog entries, I'll share my previous experience of working with PPG, ECG and Impedance measurement following traditional method. And I'll share my plan on how ADPD4100 can be used to measure all these parameters.
upcoming blogs-
BLOG 02: Pulse Oximetry - SpO2 using PPG following traditional method - Transimpedance amplifier
BLOG 03: ECG using bio-potential - instrumentation amplifier
BLOG 04: Impedance measurement for dehydration or respiration using tetra polar bio-impedance technique.

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