﻿ HOW TO DESIGN EMG SENSOR

# SPIRO THE TECH GURU

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## HOW TO DESIGN EMG SENSOR

EMG:Electromyography

Measuring muscle activation via electric potential.

application:

-medical research

-diagnosis of neuromuscular disorders

components required:

Circuit Chips:
3x TL072 IC Chip
1x INA106 IC Chip

Cables and Electrodes:
3x EMG Electrodes

Power
2x 9V Battery

Capacitors
• 2x 1.0 uF Tant capacitor
• 1x 0.01 uF Ceramic Disc
• 1x 1.0 uF Ceramic Disc

Resistors
• 3x 150 kOhm 1%
• 2x 1 MOhm 1%
• 2x 80.6 kOhm 1%
• 6x 10 kOhm 1%
• 1x 100 kOhm variable resistor
• 1x 1 kOhm 1%

other:
• 2x 1N4148 Diode

## POWER SUPPLY:

positive terminal of battery 1 connected to the negative terminal of battery 2) then measure the voltage from the negative terminal of battery 1 and the positive terminal of battery 2, the measured voltage is equal to the summation of the voltages of battery 1 and battery 2.

we want a +9V and a -9V power supplies. If we connect our two 9V batteries in series, we will get a power supply of +18V. So  we  can get the -9V and +9V.

## SIGNAL ACQUISITION:

INA106 IC :

The INA106 is a difference amplifier which will measure and amplify (G=110) the very small voltage differences between the two electrodes you place on your muscle.

## SIGNAL CONDITIONING - Amplification:

We are going to first build an inverting amplifier with a gain of -15. To do this, we’ll need one of the TL072 chips.

## SIGNAL CONDITIONING - Rectification:

we will be rectifying the signal using an active full-wave rectifier . Our rectifier will take the negative portion of our signal and turn it positive so the entire signal falls within the positive voltage region. we need both 1N4148 diodes, and a second TL072 chip.

## SIGNAL CONDITIONING - Smoothing + Amplification:

we will be using an active low-pass filter to filter out the humps of our signal to produce a smooth signal for our microcontroller.

we  will need the last TL072 chip (chip D), the two 80.8 kOhm resistors, the 100 kOhm trimmer, the 1 kOhm resistor and the 1.0 uF ceramic disc capacitor.