Medical Solenoid Valves: Principles & Applications Guide

A medical solenoid valve is an exacting electromechanical device that regulates the movement of fluids such as gases and liquids in medical devices. The valve is able to change electrical energy into mechanical movement, which enables it to open and close the channels containing fluids on its own.

These medical solenoid valves are very important in modern medical facilities because they enable the management of fluids with great accuracy.

A medical solenoid valve is commonly used in medical devices such as life support devices, ventilators, oxygen concentrators, infusion devices, and laboratory diagnostic devices. The medical solenoid valve is the best choice when there is a need to control fluids with great accuracy because it is very small and reliable.

The basic idea that makes medical solenoid valves work is the application of electromagnetic principles.

State of Energy

The coil generates a magnetic field when it is connected to the electricity source.

The plunger is attracted by the magnetic field and is pushed against the spring.

When the plunger is pushed:

The opening is pushed open.

The valve starts to open and allow the gas and fluids to pass through.

State of No Energy

When there is no electricity:

The magnetic field is destroyed.

The spring pushes the plunger back.

The opening is closed.

Control by Electronics

The medical solenoid valve is normally controlled by the medical device controller through electronic signals.

There are a few important parts that make up a typical medical solenoid valve.

1. Coil of Electromagnetic Energy

The coil is made of insulated copper wires that can be used in medical applications. When the coil is connected to power, it generates the magnetic force required to open the valve.

2. Armature/Plunger

When the coil is connected to power, the movable magnetic core opens or closes the valve orifice.

3. The Body of the Valve

Materials used to build the valve include:

316L Stainless Steel

Titanium

PEEK

PPS

Brass

These materials have been selected because they can withstand corrosion, they are safe for living things, and they have low probabilities of contaminating the human body.

4. Diaphragm/Seals

Some of the FDA-approved materials used as sealing agents include:

Silicone

EPDM/PTFE

FFKM

These ensure that there is no leakage and that the chemicals can be mixed.

5. Spring to Return

When the power is disconnected from the valve, the spring returns the plunger to its original position.

6. Orifice/Flow Port

This is a passage that has been machined very carefully.

7. Screen for filtering

This is used at the entrance of the valve to prevent the entry of contaminants.

There are several different types of medical solenoid valves.

1. Solenoid valve that works directly

This type of valve is opened or closed by the electromagnetic force.

Best for micro fluids and low pressure control.

2. Solenoid Valve with Pilot Control

Uses the pressure in the system to assist the valve in its operation.

Best for higher flow rates.

3. Valve with Two Ways

For controlling flow with simple on and off control.

4. Solenoid Valve with Three Ways

For controlling flow and routing it through two different paths.

5. Small Medical Solenoid Valve

For ultra-compact applications in medical devices where portability is a requirement.

The requirement for medical solenoid valves is increasing rapidly with the advancement of medical automation and portable medical devices.

1. Very precise control of fluids

Medical applications require precise control of fluids and gases.

2. Quick Time to Respond

They can perform in as little as one millisecond, which is great for medical applications like ventilators and respiration control.

3. Small Size

The small size of the valves allows for the creation of medical devices that can be moved.

4. Very Reliable

Valves are designed to perform for millions of cycles.

5. Simple to connect to electronic systems

The microcontrollers and control systems make it easy to control the solenoid valves.

1. Very precise

Allows for precise control of micro flow rates in drug delivery systems.

2. Quick Response

Good for medical applications where movement is needed, like medical ventilators.

3. Small Size

Good for medical applications where movement is needed.

4. Very Safe

The closed-loop design reduces the risk of leakage.

5. Clean Design

A lot of medical valves are designed for easy sterilization and are free of contaminants.

Medical valves are limited in some ways, despite their importance.

1. More expensive

Using medical-grade materials and obtaining certifications makes things more expensive.

2. Blockage Risk

If filtration is inadequate, small holes in the valve can clog up.

3. Making heat

Heating of the coil can occur when it is continuously energized.

4. Limited Flow Capacity

The small valves are designed for applications where accuracy is needed, not flow rate.

Medical valves are very important in many medical facilities.

1. Equipment for breathing and ventilation

Ventilators

Oxygen concentrators

BiPAP and CPAP machines

2. Systems for Infusion and Drug Delivery

Pumps for infusion

Syringe pumps

Systems for delivering insulin

3. Tools for Diagnosis

Analyzers for blood

Analyzers for urine

Analyzers for breath

Analyzers for tissue and gas

Analyzers for glucose

Analyzers for cholesterol

Analyzers for thyroid

Analyzers for pregnancy

Machines for Dialysis

Systems for In Vitro Diagnosis

4. Systems for Surgery and Anesthesia  

Systems for Anesthesia Gas

Medical Suction Equipment

Robots for Surgery

5. Automation in the Lab  

Systems for Switching Fluids

Equipment for Processing Samples

Proper maintenance can significantly extend valve lifespan.

It is very important to pick the best medical valve to ensure that medical devices are safe and reliable and perform optimally. The first thing to consider is the type of gas or liquid you want to control with the medical valve. Medical valves must be able to handle medical fluids such as oxygen, air, saline solution, and pharmaceuticals. Medical devices must be able to withstand the harsh effects of these fluids without rusting or corroding, and this is achieved by using chemically and biologically compatible materials such as PEEK, stainless steel, and medical-grade polymers.

The pressure and flow rate of the medical devices must be taken into account as they are very crucial in the selection and application of medical valves. The medical valve must be able to withstand the pressure and provide the exact rate required in the medical devices. In some medical devices such as infusion pumps and other microfluidics devices, miniature solenoid valves with small orifices must be used.

For some medical devices such as ventilators, breathing equipment, and anesthesia, the response time and accuracy must be very fast and reliable since the medical devices must be able to respond to the medical conditions and changes as required by the patients.

It is also important to consider the voltage and the power consumption of the medical valve since it must be able to perform optimally with the medical devices that it is required to control. The medical valve must be able to withstand the medical tests and must be approved by the FDA.

An engineer can choose the best medical valve that works best and is safe for the patients by considering the above factors.

Medical solenoid valves play a big part in the development of medical technology. It is very important that they function correctly to ensure the safe, accurate, and reliable flow of fluid and gas through medical equipment.

Some of the advantages of medical solenoid valves include:

Very accurate

Fast response time

Small

Work very well

Simple electronic control

Medical automation, portable healthcare devices, and medical diagnostics continue to grow at a very fast pace. Therefore, medical solenoid valves will be very important in the future.

To select the best medical valve, one has to look at the type of fluid used, the pressure at which it will be used, the response time, voltage, duty cycle, the type of material used, and the rules to be followed.

A well-designed medical valve does not only make a medical device function well, but it also makes a patient safer.