Brief description

A syringe is a simple reciprocating pump consisting of a plunger that fits tightly within a cylindrical tube called a barrel. It is used to inject liquids into or withdraw them from the body or other systems.

Use / Function

• Medical: Injecting medicines or vaccines, withdrawing blood or other fluids, and irrigating wounds.
• Industrial: Precise application of lubricants, adhesives, or measuring small quantities of liquids.
• Scientific: Transferring precise volumes of reagents in a laboratory.

Operating principle

Suction and Pressure:

1. Withdrawal: Pulling the plunger back increases the volume inside the barrel, creating a vacuum (lower pressure) that sucks fluid in through the orifice.
2. Injection: Pushing the plunger reduces the volume, creating pressure that forces the fluid out through the orifice.

How to create it

1. The Barrel

• Use a transparent, heat-resistant tube (ideally borosilicate Glass or Plastic).
• One end must have a small tapered opening (nozzle) to attach a needle or tube.

2. The Plunger

• A rod made of metal or plastic that fits closely inside the barrel.
• The tip must have a seal made of Natural Rubber or leather to ensure it is airtight and watertight.

3. The Needle

• A hollow tube made of Stainless Steel.
• Requires advanced manufacturing (drawing metal into fine tubes) and sharpening.

4. Assembly

• Ensure all parts are clean and the seal is lubricated with a compatible substance (like medical-grade silicone or Vegetable Oil for non-medical use).

Materials needed

• Barrel: Glass, plastic, or even high-quality wood/bone (for very primitive suction).
• Plunger: Metal or plastic rod.
• Seal: Natural Rubber or oiled leather.
• Nozzle/Needle: Metal (preferably stainless steel).

Variants and improvements

• Glass Syringes: Reusable and easy to sterilize by boiling.
• Disposable Syringes: Made of plastic, intended for single use to prevent cross-contamination.
• Bulb Syringe: Uses a flexible rubber bulb instead of a plunger.
• Hypodermic Needle: A very fine, hollow needle capable of penetrating skin without causing significant trauma.

Limits and risks

• Contamination: If not properly sterilized, syringes can transmit deadly diseases (HIV, Hepatitis). See Sterilization.
• Air Embolism: Injecting air into a vein can be fatal. All air must be expelled before injection.
• Fragility: Glass syringes can break easily.
• Precision: Worn seals can lead to leaks and inaccurate dosing.