Question

Explain the followings
1- The differences between the designed circuit for the spirometer and ventilator.
2- The differences between the designed circuit for the ECG and EMG? I suggest to you to track the difference stage by stage from the measurement to the final manipulation.

Answer 1

1 Spirometer Vs Ventilator

Spirometer: It is a biomedical device used to measure Lung capacity and lung volume.

Construction of spirometer consist of Gas collecting champer.There are types of spirometer such as wedge spirometer,Ultrasonic spirometer and Water seal spirometer.To understand construction we take water seal spirometer.

It consists Water filled cylinder,Upright,Inverted Weighted bell jar.Also the breathing piping is attached with bell jar.The cylinder capacity about 6 to 7 liters.The bell jar is situated inside the cylinder.

Working : Person breath into the bell through pipe,the volume inside the cylinder get changed.Then the change in volume is converted into vertical motion of the bell jar hence the hanging weight get changed it happends due to the string is attached with weight via pulleys.During each cycle of inhalation and exhalation jar moves up and down.The weight attached to string moves according to the movement of the bell jar.A measuring pen is attached with weight which draw the graph on paper.This graph is known as Kymograph.The electrical signal is produced according to the movement of weight which produce a display on the instrument screen.

Ventilators

The ventilator also a medical equipment used to support breathing.This is done by removing carbon diaoxide from lung and provid oxigen into the lung

Working: A ventilator uses positive pressure to blow the air into lungs.Patiend exhale their own.A monitor is used to control the amount of oxigen is going to the lungs.Also monitor can send alarm signal to caregiver when increase in air pressure.

Construction

It consists of nasogastric tube which goes through nose into the stomech.Endotracheal tube which is through mouth into the windpipe.Mechanical ventilator blows air.There will be two seperate path for inhale air and exhale air.

2 ECG Vs EMG

ECG

An ECG is representation of the electrical activity of the heart muscle.The cardiac muscle contracts in response of electrical depolarisation of muscle cells.So the ecg is taking by the sum of this electrical activity.

Circuit design

In the circuit amplifier take input from self sticking electrode which is attached to the body.Amplification is must because the signal is small.Also amplifier can suppress noise.Connect the electrode with circuit as short as possible and well shielded.Diod protection is given to the amplifier.The circuit run with only two 9v battery.For the output signal a bulkheaded BNC connector is mounted on the circuit box.

EMG

Electromyography is the method for calculating and register thevaction potential of muscles.The device used for this is called electromyography and the record is known as electromyogram.

Circuit design

It consist of EMG electrode which is used to EMG recording.Bioelectric amplifier used to amplify the bioelectric signal.Af amplifier the measuresd emg can be visualize through oscilloscope by using AF amplifier.Oscilloscope used for visualizing EMG.EMG recorder is used for recording low frequency emg signals.