The process principle of colloid osmometer is based on the selective permeation and pressure balance mechanism of semi permeable membrane. The specific implementation process is as follows:
1、 Core Process Principles
1. Selective permeability through semi permeable membranes
The instrument uses semi permeable membranes with specific pore sizes (such as cellulose sulfate membranes, polysulfone membranes, etc.), allowing only water molecules and electrolytes to pass through while preventing colloidal particles (particle size 1-1000nm) from penetrating.
2. Measurement pool structure design
Lower half of the pool: a closed structure filled with a reference solution containing electrolytes (such as Ringer's solution).
Upper half cell: an open structure that accommodates the colloidal solution to be tested, separated from the lower half cell by a semi permeable membrane.
3. Permeation pressure difference and pressure equilibrium
When the osmotic pressure of the colloidal solution is higher than that of the reference solution, water permeates from the lower half of the tank (low osmotic pressure side) to the upper half of the tank (high osmotic pressure side).
During the infiltration process, negative pressure is generated in the lower half of the tank due to liquid loss, until the static water pressure and colloid osmotic pressure reach equilibrium.
4. Pressure detection and signal conversion
The lower half of the pool is equipped with an electronic pressure sensor that converts changes in static water pressure into electrical signals, which are amplified and displayed or output in pressure units (such as mmHg).
2、 Key process components
1. Semi permeable membrane module
Material requirements: high chemical stability, uniform pore size, ensuring that only solvents and small molecules are allowed to pass through.
Fixed method: Sealed installation is required to avoid leakage, usually using card slots or compression devices.
2. Pressure sensing system
Sensor type: High precision electronic pressure sensor (such as resistive or capacitive).
Signal processing: Integrated temperature compensation and linear calibration functions to improve measurement accuracy.
3. Measurement pool design
Material: Corrosion resistant material (such as stainless steel or special polymers).
Structural optimization: Reduce dead volume to ensure rapid attainment of permeation equilibrium.
3、 Typical application process
1. Sample preparation: Inject the colloidal solution into the upper half of the cell to ensure there are no residual bubbles.
2. Balancing process: static or low-speed stirring to accelerate infiltration, usually taking several minutes to tens of minutes.
3. Data reading: After the pressure stabilizes, directly read the values on the display screen or export the data through software.
4、 Technical features
1. High precision: The resolution of the pressure sensor can reach ± 1mmHg.
2. Quick measurement: Some models can be tested within 5 minutes.
3. Automation: Modern instruments integrate temperature control, automatic calibration, and result storage functions.
This process combines physical permeation with pressure sensing to achieve non-destructive quantitative detection of the osmotic pressure of colloidal solutions.