Installations, apparatus and instruments for analytical-chemical process analysis and for biotechnology process analysis, namely, bioreactors and parts thereof for the cultivation of living mammalian or plant cells in vitro in the field of research and development in the pharmaceutical, petrochemical, food and agricultural sectors, bioreactor for cell culturing, electronic monitors for alcohol fermenters and anaerobic fermentation devices that monitor microbial activity, bioreactor control instruments, electrical controls that regulate oxygen level, airflow, temperature and acid levels within bioreactors, liquid mixers for laboratory use, namely, biological mixers for mixing liquids in bioreactors, acoustic resonance cell retention systems comprised of piezo-electric transducers fitted into a resonance chamber for inducing a standing wave acoustic force field to allow perfusion, concentration and washing of cells or micro-organisms, pH sensors, dissolved oxygen (DO) sensors, glucose sensors not for medical purposes, optical cell analyzers for measuring cellular concentrations, wet-chemical analyzers for the analysis of liquids in chemical processes