Overview
The EVOM3 Epithelial Voltohmmeter is a precision instrument designed for measuring transepithelial electrical resistance (TEER) in cell culture models. Developed by World Precision Instruments, it has become an industry standard for assessing epithelial barrier function in pharmaceutical research, toxicology studies, and basic biomedical research. The device provides researchers with quantitative data about the integrity and permeability of cell layers, particularly in models like Caco-2 or MDCK cell cultures. Its non-invasive measurement capability allows for repeated monitoring of the same culture over time, making it invaluable for longitudinal studies of barrier function development or compound effects.
Structure and Working Principle
The EVOM3 system consists of a main measurement unit, detachable electrodes (either chopstick or EndOhm style), and optional data logging accessories. The device applies a small AC current (typically 12.5 Hz) across the cell monolayer and measures the resulting voltage drop to calculate resistance. Key components include a precision current source, sensitive voltage measurement circuitry, and temperature compensation algorithms. The chopstick electrodes are designed for use with standard cell culture inserts (e.g., Transwell), while the EndOhm chamber provides more standardized measurements for specific applications. The system's alternating current approach minimizes polarization effects that could distort measurements.
Key Features
The EVOM3 offers several advanced features that distinguish it from basic resistance meters. These include automatic temperature compensation that adjusts readings to 37°C equivalents, regardless of ambient conditions. The device also provides multiple measurement ranges (from 0-20 kΩ to 0-100 kΩ) to accommodate different experimental needs. Additional features include a compact, portable design suitable for use in biosafety cabinets, battery operation for field use, and optional computer interface capabilities. The system's proprietary electrodes are designed for minimal disturbance to cell cultures during measurement, with sterilizable components that maintain aseptic conditions.
Application Areas
Primary applications of the EVOM3 include pharmaceutical permeability studies (predicting drug absorption), toxicology assessments (barrier damage by compounds), and basic research into epithelial physiology. It's particularly valuable in developing in vitro models of intestinal, pulmonary, or blood-brain barriers. The device is widely used in academic research laboratories, pharmaceutical development departments, and contract research organizations. Recent applications have expanded to include quality control in tissue engineering and monitoring of organ-on-chip systems. The ability to track TEER changes over time makes it useful for studies of inflammatory responses, tight junction regulation, and pathogen interactions with epithelial barriers.
Maintenance and Precautions
Proper maintenance of the EVOM3 ensures measurement accuracy and prolongs instrument life. Electrodes should be cleaned with 70% ethanol after each use and stored dry. Regular calibration checks using provided standards are recommended, with professional servicing every 2-3 years. Key precautions include avoiding contact between electrodes and conductive surfaces during measurement, maintaining sterile technique when working with cell cultures, and protecting the instrument from liquid spills. The electrodes are delicate and should be handled carefully to avoid bending or damaging the sensitive measurement tips. When not in use, the device should be stored in a clean, dry environment.
B2B Procurement Guide
When procuring EVOM3 systems for laboratory use, consider the specific needs of your research applications. The standard package typically includes the main unit and chopstick electrodes, while EndOhm chambers and data acquisition accessories may require additional purchase. Bulk purchasing for multiple laboratories may qualify for institutional discounts. Lead times for new units are typically 4-6 weeks. Consider service contracts that include periodic calibration and maintenance. For specialized applications, consult with the manufacturer about custom electrode configurations or integration with automated culture systems. Used units may be available through laboratory equipment resellers, but verify calibration status and electrode condition.
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