Getting started with the E3K platform

E3K aims at providing an affordable, fully open-source, wireless framework for an intuitive understanding of bio-signals originating from the human heart, muscle, and brain. The platform consists of the following modules:

• Wi-Fi and BLE enabled Data Communication and Processing Unit (DCPU)

• Electromyography (EMG) sensor - to capture muscle movements

• Electrocardiography (ECG) sensor - to capture heart signals

• Electroencephalography (EEG) sensor - to capture brain activity

• 9-DoF Inertial Measurement Unit (IMU) - to capture motion

These modules, combined with our firmware and data collection software, enable a reliable and high rate of data acquisition at an affordable price-point.

This guide provides essential information for getting started with the E3K platform.

Required Materials

Following are the items that are required for following this guide. All the items are provided in the E3K combo.

• DCPU

• EMG sensor

• ECG/EEG sensor

• IMU

• Sensor electrode Cable

• Disposable electrodes

• USB Mini-B cable

• 3.7V battery (optional; not included in Combo)

Before proceeding, it is advised to go through the datasheet of each of the modules to get familiar with voltage and current limitation. The datasheets are available on the WallySci website (https://www.arduino.cc/en/software).

Procedure

Following instructions provide step by step guide for installation of required software and wiring of the hardware.

• Install Arduino IDE. The first step is to install Arduino IDE and get yourself familiarised with the software. The software can be downloaded from Arduino website (https://www.arduino.cc/en/software). There are a few versions of this software, including an online editor, installation file and portable version. It is recommended to download the installable version based on the operating system. If you are unfamiliar with Arduino and ESP32, there are many online resources for learning the platform. Links for some of the tutorials are provided in the “Reference Links” section below.

• Installing ESP32 core. Once Arduino IDE is installed, the core for ESP32 has to be installed. The following links provide detailed instructions on how to install the ESP32 core using Arduino IDE.

  • https://github.com/espressif/arduino-esp32/blob/master/docs/arduino-ide/boards_manager.md

  • https://randomnerdtutorials.com/installing-the-esp32-board-in-arduino-ide-windows-instructions/#:~:text=Installing%20ESP32%20Add%2Don%20in%20Arduino%20IDE&text=Open%20the%20Boards%20Manager.,installed%20after%20a%20few%20seconds

• Placing electrode pads. Electrode placement plays a vital role in the quality of data to be captured. The position is different for different types of signal. As an example, an ECG sensor is used in this guide. However, similar steps are required for the other sensors.

Place the electrodes as shown in the image below. The reference electrode (Black) has to be placed on the left-leg ankle or at the back of the left-hand palm (or somewhere close to the bone with least muscle activity). Out of the other two electrodes, place one (Red) on the right-hand wrist and the other (Blue) on the left-hand wrist.

Placement of the electrode (red dot is the reference electrode) (credit: Wikipedia.com)

Note: Although the electrode pads are reusable, the quality of signals depends on the state of the pads.

• Connecting electrode cable. Connect the electrode cable to the 3.5 mm jack of the ECG sensor, as shown in the figure.

• Connecting a sensor. The DCPU board contains 6 analog ports (3 on each side). Each port has three connections - ground, VCC and analog pin. Therefore, any of the ports can be used. Connect the ECG sensor to the DCPU sensor, as shown in the figure below.

Connections between DCPU and ECG sensor

• Connecting DCPU. Simply connect the DCPU to the computer via a micro-USB cable.

• Uploading the code. Download the “Getting started” Arduino code from the WallySci website (https://www.wallysci.com/post/downloads). Open the code and select “ESP32 Dev Module” in “Tools> Board:”. Select the appropriate port in “Tools>Port.” Finally, upload the code.

• Visualize the signals. As mentioned earlier, the sensor is connected to pin 35, which is the default pin in code. Open the “Serial Plotter” via going to “Tools>Serial Plotter”. The plotter should output the signal similar to the following image.

Sample EMG Data as seen on Arduino IDE Serial Monitor

To change the pin number, enter one of the following commands in the input box at the bottom of the Serial Plotter. Moreover, the code can also be modified according to the application.

Note: Remove the charger from the laptop and move the laptop, DCPU and sensor cable away from the AC power supply to avoid AC interference in the signal. Instead, the board can also be powered and can communicate with the laptop via Bluetooth. Sample code available on the WallySci website (https://www.wallysci.com/post/downloads).

• Test other sensors. The above steps can be applied to all the other biosensors by changing the electrode positions. For IMU, follow the link provided in the “Reference Links” section. Please note that the default configuration of the IMU is I2C. For SPI and UART, soldering will be required.

Follow the other tutorials on the wallySci website for in-depth explanations of different projects.

Reference links

• Datasheets

  • https://www.wallysci.com/post/downloads

• Arduino software

  • https://www.arduino.cc/en/software

• ESP32 Core

  • https://github.com/espressif/arduino-esp32/blob/master/docs/arduino-ide/boards_manager.md

  • https://randomnerdtutorials.com/installing-the-esp32-board-in-arduino-ide-windows-instructions/#:~:text=Installing%20ESP32%20Add%2Don%20in%20Arduino%20IDE&text=Open%20the%20Boards%20Manager.,installed%20after%20a%20few%20seconds

• Esp32 tutorials

  • https://www.youtube.com/watch?v=_0eHPrRC8oc&list=PLfPtpZzK2Z_QO8snrdnRTTNtQvLw35Zfc&index=1

  • https://www.youtube.com/watch?v=5CkGpAai_aI&list=PLruzZCuhcsGNFXfOPUfNqdhP3-7_Hh7F0&index=2

• Sample Code

  • https://www.wallysci.com/post/downloads

• IMU Instructions

  • https://learn.sparkfun.com/tutorials/qwiic-vr-imu-bno080-hookup-guide

• WallySci Projects

  • https://www.wallysci.com/blog