Breathing Machine. Design Requirements Provide/Remove 500cc of air Rate ≈ 15 breaths per minute Ability to vary volume of air, and rate Age (years)Weight.

Breathing Machine

Design Requirements Provide/Remove 500cc of air Rate ≈ 15 breaths per minute Ability to vary volume of air, and rate

Age (years) Weight (kg) Tidal Volume (cc)

Child 10 33 200 - 270

Teenager 17 55 330 - 440

Adult 73 440 - 580

Existing Breathing Machines The need for artificial breathing mechanism has

always been around with human history

1896: O’Dwyer used a foot operated pump which blew air into patient’s lungs through a curved metal tube

Existing Breathing Machines

Current Respirators Air-Shielded Electric Ventilators

Mörch Piston Ventilators

Bennett Respirators

Existing Breathing Machines

Air-Shielded Electric Ventilators Blows atmospheric air into

the lung using an electric powered blower that compresses and expands rubber bellows inside a rigid container

Uses one-way valve

Only works for inhalation

Existing Breathing Machines: Air-Shielded Electric Ventilators

Mörch Piston Ventilators Uses a circular plate

with a rod connected to a piston

Motor provides force

Circular plate controls volume

For either inhalation or exhalation

Existing Breathing Machines: Mörch Piston Ventilators

Bennett Respirators Operates with patient’s

initiation

Patient breaths in, low pressure causes spring to pop, and the valve opens since it is connected to the spring diaphragm

Compressed air comes in until the pressure difference between either side of the valve becomes small

Existing Breathing Machines: Bennett Respirators

Inhalation

Exhalation

No tilting of the plateOUTER BEAM

INNER BEAM

MUSSL Breathing Machine

Machined Components Casing Cam Supports Cams Beam and Slider Bellows Plate

Weight & Sealing Plexiglass

Design Justification: Choice of Materials

How it works…

Fully-Compressed(2 inches)

Fully-Expanded

(12 inches)

Neutral position

Expansion

Fresh Air

Neutral position

Fresh Air trapped

Exhaust Air from the lung

Exhaust Air trapped

Allowed Flow Direction

Compression

Neutral position

Trapped Exhaust Gas escapes to ambient

Trapped Fresh Air flows into the lung

Fully-Expanded

IssuesProblems: 1) Difficulty in synchronizing 2 motors 2) Severe sliding of outer beam along inner beam

- leads to bending of the bellows

Bending of the bellows

Plate remains HORIZONTAL

The Final Design

3D-Model

Bellows Guide

1 MotorTiming Belt and Pulleys

Breathing Rate Control Variation of motor speed

Method1. Resistive speed control2. PWM speed control

Design Description: Breathing Rate Control

Resistive Speed Control

R1 = motor, R2 = resistor Resistor reduces voltage delivered to motor Simple to implement Extreme inefficiency and possible danger

Design Description: Breathing Rate Control

PWM Speed Control

PWM: Pulse Width Modulation Splits voltage supply into pulses and controls the

pulse width, hence the total voltage Each pulse carries full voltage & torque

Design Description: Breathing Rate Control

PWM Circuit

Design Description: Breathing Rate Control

Performance Provide/Remove 500cc of air

Rate ≈ 15 breaths per minute

Ability to vary volume of air

Ability to vary breathing rate

Machine Testing

Integration with Lung Model