Various microbioreactor prototypes have been presented in the literature. However, only a few have managed to become widely used in industry and even fewer (if any) have become an industry standard. We therefore present a versatile microbioreactor device for batch and continuous cultivation of suspended cells which combines the small working volumes known from microwell plates with the versatility of bench-scale reactors. Additionally, this device is designed for single-use which significantly reduces the workload before and after the actual cultivation. The device presented here is cylindrical, consists entirely of polydimethylsiloxane (PDMS), and has outer dimensions of 14 mm diameter and 4.2 mm height. The reactor chamber is a cylinder with 8 mm diameter and 2 mm height resulting in a volume of 100 mu L. Homogeneous mixing of the broth is achieved with a free-floating stirrer bar which also provides the updraft necessary to keep cells in suspension. Temperature and pH can be tightly controlled to the desired set point; dissolved oxygen (DO) and cell density (via optical density, OD) are also measured on-line. Aeration is provided through a semipermeable membrane which separates the gas from the liquid phase. pH is controlled by addition of CO2 and NH3 gas through the same membrane. Last but not least, the reactor has been designed with simplicity in mind, such that the final design can be bought pre-sterilized and discarded with other lab-waste after use. (C) 2010 Elsevier B.V. All rights reserved.