ECG Click

This is an ECG (or EKG) machine on a click board. It measures the electrical activity of a beating heart through electrodes taped to the skin. The board requires little setup, and the final measurement results can be displayed as an Electrocardiogram using a free Windows app.

With the ECG click bundle (click + cable + electrodes) you will be able to prototype your own health-tracking and fitness devices, quantified-self wearables… or you can just make an LED blink in sync with your heart.

Setup guide: from heart to skin, from skin to 3.5 mm jack

To start recording ECG you will need:

• 1. ECG click
• 2. Cable
• 3. Disposable adhesive electrode pads (sold in packs of 30)

If you are starting out, the best offer is the ECG click bundle that contains all three, saves you $8.

Of course, you will also need a target board with an MCU with at least a 10-bit ADC (preferably powered from an external battery).

The three electrodes are connected to your left shoulder, right shoulder, and to the left side of the abdomen (below the heart). The last one can also alternatively be fitted on the left leg.

The electrodes are connected to the board with a cable that plugs into the onboard 3.5mm phone jack.

See the docs page for more detailed instructions.

Circuit design: amplifying and filtering the raw signal

By the time it reaches skin surface, the electrical signal from the heart becomes faint. Only few miliVolts. This weak signal is also obstructed by muscle activity from the rest of the body.

Another source of noise is the electromagnetic interference from the environment (the body can act as an antenna).

But the pattern of a beating heart is fairly predictable. This allows us to design circuitry that properly amplifies and filters the electrical signal to get the desired output.

ECG click has a 7 block design. It comprises ESD, overvoltage and overcurrent protection (protecting both the hardware and the person), a pre-amplifier and amplifier, two high-pass filters, a low-pass filter, and a DRL circuit.

Learn more about the hardware design from the docs.mikroe.com page.

Plot your heart beat

MikroPlot is a free data visualization tool (Windows) that can be used to generate an ECG.

The graph is generated from data sent from the MCU (ADC values from ECG click input + time stamp). A UART-USB connection is required.

See the learn.mikroe.com article for more information.

Applications

• Make a portable battery-powered holter with ECG click, microSD click and clicker 2
• Quantified-self data logging: subtle variations in your heart-rate occur from second to second. With ECG click you are not limited to the doctor’s office. Record ECG while you watch TV, read email, talk over the phone – study patterns to see what excites you (HRV – heart rate variability is a good indicator of state of mind).
• Pair ECG click with a wireless transceiver to transmit a heartbeat signal to various electronics (set a LED strip to pulsate in sync with your heartbeat, or the vibro motor on another person’s Hexiwear).

Features

• 7-block design (protection, preamplifier, high-pass filter #1, amplifier, high-pass filter #2, low-pass filter, DRL circuit
• Ready-to-use example and free software tool to generate ECG plot
• Jumpers for setting output voltage range
• Trimmer potentiometer to adjust gain
• MCP609 OpAmp
• MAX6106 Voltage Reference IC
• ESD, OverVoltage and OverCurrent protection
• Analog output (mikroBUS™ AN pin)
• 5V power supply