Calibration of Microbalances
Balances and scales have been in use for over four thousand years. These instruments have proven invaluable for commercial transactions to determine the weight of a material for sale. Microbalances operate at a very high level of precision. They can display weight readings down to microgram levels or, in the case of quartz crystal microbalances, below the nanogram scale.
Microbalances are used in a wide array of applications, where small levels in weight variation can make a big difference. These instruments are often found in product testing and quality assurance labs to ensure compliance with exacting production standards. Medical device researchers use microbalances for checking uniformity in critical components. Precision scales also play a role in chemistry labs and mining to measure small amounts of powders and minerals.
Typical Fields for Applications
- Medical Devices
- Pharmaceutical Production
- Quality Assurance
As microbalances are often used in quality assurance applications, repeatability of measurements is absolutely critical. Unfortunately, microbalances use small amounts of force as a reference to measure mass. If vibration or acoustic noise levels vary from moment to moment, obtaining repeatability of test results is difficult to achieve. Often microbalances have no external means of determining noise levels, so inaccurate readings can go undiscovered for many days or production cycles. Monitoring noise levels and controlling the microbalances’ environment is a necessary step in using these sensitive instruments.
When the load cell of a microbalance is disturbed, either by sample loading or an environmental disturbance, the instrument will need to settle completely before accurate measurements can be taken. Therefore, a vibration isolation system’s settling time is a key criterion affecting the throughput of these instruments.
In addition to sensitivity to vibrations and acoustics, microbalances are also very sensitive to exposure to air currents, dust, and thermal fluctuation. For this reason, microbalances should be placed in a hood or acoustic enclosure when in use.