title: A fast voltage-controlled continuous-flow miniature chemostat.
abstract: A continuous-flow mixing device was developed for fast concentration changes in a 0.25 microliter volume. The mixing chamber is designed to study the effects of fast concentration changes in the bathing solution on small probes (e.g. chemoreceptive hairs or membrane patches). It consists of a freely accessible hanging droplet which is viewed with a microscope. Mixtures are generated by injecting variable amounts of a fluid into another fluid under photometric control. Time courses for the concentration steps are (computer-)generated as voltage-time courses which serve as set point of the injection-control servo circuit. Positive steps of the concentration of the injected fluid can be reached within less than 30 ms; falling concentrations are determined by wash-out time constants around 100 ms.
mesh_terms: D000818:Animals; D002628:Chemoreceptor Cells / Q000502:physiology*; D004594:Electrophysiology / Q000295:instrumentation* / Q000379:methods; D008845:Microinjections / Q000295:instrumentation / Q000379:methods