Have you ever wondered how you could control a robot arm for gaming applications? Or perhaps how you could measure muscle activation? The key to your curiosity lies with the EGM sensor.
EGM or electromyography is crucial for medical research and neuromuscular disorder diagnostics. Also, the invention of powerful integrated circuits and microcontrollers has brought about EMG sensors in robotics, prosthetics, and other control applications.
However, EMG remains expensive and out of reach for many engineers and hobbyists alike. Luckily, we’re here to show you how to build an EMG sensor for your next project.
What are the Uses of EMG Sensors?
The primary purpose of an EMG sensor is to measure the little electrical activities of resting and contracting muscles of the hand movements. For example, the measured muscle movements are moving the arm, clenching the fist, snapping the fingers, etc.
But it doesn’t erase the fact that different people use EMG sensors for various applications.
For example, some use EMG sensors for clinical and biomedical purposes like attaching prosthetics, neuromuscular diseases, and motor control disorders. In contrast, others use them for control applications like robotics, motion detection, etc.
How do EMG Sensors Work?
In truth, EMG sensors measure what we call EMG activity. This activity relates to the amount of contraction your muscles produce and the number of contracting muscles. The EMG sensor can measure this activity in microvolts.
Also, the amount of voltage amplitude an EMG sensor records depends on the muscle contraction strength. In other words, the stronger the muscle contraction, the more muscles activate, thus generating a higher voltage amplitude.
Interestingly, placing electrodes near muscle groups can help you record EMG activities or signals. When muscles activate, it decreases the muscle length and allows the skin and electrodes to move. As a result, the electrodes record the electrical activity or signals of the active muscle fibers when contracting.
Types of EMG Sensors
There are two major EMG sensor types, which include the Surface EMG sensors and inserted EMG sensors. Even though they are two different sensors, they have similar procedures.
1. Inserted EMG Sensors
There are two types of inserted EMG sensors; Needle sensors and Fine-wire sensors. Let’s take a closer look at these two sensors.
(i) Needle EMG Sensors
You can find these kinds of EMG sensors mostly in clinical procedures for neuromuscular evaluations.
Here, we have an essential needle tip that you can use as a detection surface. How? The needle contains an insulated wire in its cannula, allowing it to detect muscle activity.
Needle EMG sensors
Source: Wikimedia Commons
(ii) Fine Wire Sensors
As the name implies, these sensors are wires, but they aren’t ordinary wires. Instead, these fine wire sensors have a small diameter, stiff, and are non-oxidizing with high-level insulation.
Also, the wire sensors have extremely fine designs that make them easy to implant and remove from skeletal muscles. The best part is these sensors aren’t as painful as needle sensors.
2. Surface EMG Sensor
While the inserted EMG sensor is an invasive technique, the surface EMG sensor does not need penetration to detect and record EMG activity/signals through the skin’s surface.
Surface EMG Sensors
Source: Wikimedia Commons
It’s easy to use these sensors, and you don’t need strict medical supervision and certification like their inserted counterparts. Also, surface EMG sensors primarily work for control applications, sports medical evaluations, motor behavior, and neuromuscular recordings.
The EMG sensor has powerful features that make it useful for medical and control projects. Here are some of the features of a standard EMG sensor :
- An EMG sensor is compatible with Grove.
- It has a 3.3v to 5v power supply voltage.
- The EMG sensor also features some 1000mm cable leads.
- You also get six disposable surface electrodes.
- The sensor features a 3.5mm connector.
- The is no need for an additional power supply.
- It supports both Arduino and Raspberry Pi platforms.
EMG Sensor Circuit with Arduino
Arduino and EMG
Source: Wikimedia Commons
While Myoware has one of the best EMG sensors, we can’t deny that it’s quite expensive. Thankfully, there are cheaper alternatives like the Grove-EMG Detector, which we’ll be using for this circuit. It has similar features from the look of things, and you can easily integrate it with a microcontroller.
Here’s what you’ll need for this project.
- Arduino board
3D illustration of Arduino board
- Grove-base shield
- Grove-LED bar
- Grove-EMG sensor (comes with the necessary cables to make connections)
Here’s how to connect your Grove-EMG detector to your Arduino to make an EMG sensor circuit:
1st step: Connect your Grove-base shield to your Arduini board.
2nd step: Next, connect your Grove-LED board to your D8 port on your Grove-base shield.
3rd step: Now, grab your Grove-EMG sensor to your base shield’s A0 port.
4th step: Finally, connect your electrodes to your EMG sensor and place them on your preferred muscle group. Ensure you keep some distance between your electrodes.
After setting your hardware, you’d need to settle things in the software area.
So, here’s what you need to do:
Step 1: First, download the Arduino code for this code here, then copy and paste it onto your Arduino Uno.
Step 2: Finally, upload the code and test your EMG Sensor circuit.
How to Test
After uploading your code, it starts initializing. Indeed, the process should take you a maximum of five seconds. During this process, the LED bar should go down from 10 to 0.
When the LED bar is off, start moving to test your circuit. You should see this bar go up and down when you move your hand accordingly.
What is the Difference Between an ECG, EEG, EMG, and EOG?
An ECG, EOG, EMG, and EEG measure some form of human activity. For example, the ECG (electrocardiogram) determines heart activity by measuring electrodes on the legs, torso, and arms.
On the other hand, EEG (electroencephalogram) monitors brain activity with electrodes on the forehead. In contrast, the EMG (electromyogram) measures muscle activities, and an EOG (electrooculogram) measures eye movement.
How Much are EMG Sensors?
The popular MyoWare muscle sensor can cost as much as $39.95. However, the more affordable Grove-EMG detector we used in this tutorial costs only $3.50.
EMG sensors are essential devices in the medical field as they help doctors achieve different biomedical applications. Such applications include diagnosing nerve and muscle disorders, medical research tools, and controlling prosthetics.
Beyond medicinal applications, EMG sensors also come in handy in controlling robots. For example, you can use EMG sensors as a controlling signal for moving robots based on your specific needs.
These are some of the things you can achieve with EMG. Interestingly, this article shows you a more affordable way to access EMG for your engineering projects.
So, do you have more questions to ask? Feel free to reach out to us, and we’ll be happy to help.