In biomedical engineering, atmosphere control most often means setting O2 and CO2 levels in cell and tissue culture environments beyond what standard incubators can deliver. The main applications are hypoxia research, controlled bioreactor culture, and 3D tissue engineering, where the gas environment is an experimental variable rather than a fixed background condition.
Hypoxia studies
Oxygen tension in human tissue varies widely. Arterial blood runs near 100 mmHg (approximately 13% O2), while tumour microenvironments, bone marrow, and ischaemic tissue can fall below 1% O2. Standard CO2 incubators maintain 5% CO2 and atmospheric O2, which is too high for physiologically relevant hypoxia studies. Cancer biology, stem cell research, and wound healing models all require stable O2 concentrations from a fraction of a percent up to physioxia (3–5%), with CO2 controlled independently. A gas mixer delivers this by blending O2, CO2, and N2 at defined ratios, verifiable against the mass flow reading of each channel.
Bioreactor culture
Growing cells in bioreactors for tissue engineering or bioprocessing requires an atmosphere that supports the metabolic state of the culture at each stage. Oxygen demand changes as cell density increases. CO2 serves as both a pH buffer source and a metabolic indicator. Dynamic control of the sparge gas composition, with the ability to ramp or step O2 and CO2 independently, allows the culture to be supported through growth, differentiation, and maintenance phases without manual intervention.
3D tissue engineering
Spheroids, organoids, and scaffold-based constructs develop oxygen gradients naturally as mass transfer limits penetration to the centre. Research on how these gradients affect cell behaviour, and on engineering constructs that tolerate or exploit them, requires the ability to set and hold the exterior O2 condition precisely over days to weeks. A gas mixer maintains the external atmosphere at any setpoint, with programmable transitions between conditions during the culture period.
Respiratory device testing
Devices that interact with respiratory gas, including breath analyzers, inhalation drug delivery systems, and research lung models, require a characterised gas supply at physiological flow rates. Known concentrations of O2, CO2, and water vapor are the baseline conditions. Some tests also require trace gas components at defined concentrations, which are produced by dynamic dilution from a parent standard.
