Two prototype 24-unit microbioreactors are presented and reviewed for their relative merits. The first used a standard 24-well plate as the template, while the second consisted of 24-discrete units. Both systems used non-invasive optical sensors to monitor pH and dissolved oxygen. The systems were used to cultivate Escherichia coli. Both designs had their merits and the results obtained are presented. In addition, dissolved oxygen control was demonstrated at the milliliter scale and 24 simultaneously monitored fermentations were successfully carried out. These results demonstrated high quality high throughput bioprocessing and provide important insights into operational parameters at small scale. ß 2005 Wiley Periodicals, Inc.

The magnetostrictive mini-actuator (MMA), with its unique characteristics such as large strain, high force and high energy density, is potentially a new claw of actuator most suitable for distributed actuator applications such as vibration control of smart structures. This paper presents a theoretical framework, validated experimentally, to develop an MMA and its feasibility for vibration control. Based on two-dimensional thermal analysis, the general form of thermoelastic mathematical model for characterizing magnetostrictive-based actuators is proposed and experimentally validated. Thermal effects, at other than the initial state, are' shown to have a significant effect on attainable strain and force of an MMA. Experimental results show that the MMA has good static and dynamic performance. and is suitable for applications in smart structures.

We present a new computer-controlled, electromechanical system for performing simultaneous extension, inflation, and torsion experiments on cylindrical segments of natural and artificial blood vessels. Specimens are tested while immersed in a temperature-controlled, oxygenated, physiologic solution. Deformations are measured within a central region of the specimen using noncontacting video methods. The associated axial loads, luminal pressures, and torques are measured with standard transducers. Data are collected and stored on-line, and are used in the feedback control of experimental protocols, which are prescribed using custom interactive software. Finally, we present illustrative data obtained from canine aortas and common carotid arteries.

This paper investigates the feasibility of using embedded magnetostrictive mini actuators (MMA) for smart structure applications, such as vibration suppression of beams. A cantilever beam, embedded with MMA and subjected to free vibration was chosen for this work. Based on the Euler-Bernoulli beam theory and the magneto-thennoelastic theory of MMA, an integrated mathematical model of the beam embedded with MMA is developed. The attenuation in attainable strain of the actuator due to embedding is investigated for two cases: pure bending and combined extension-bending actuation. Simulation, usino an oDen-looD control-scheme. shows that it is Dossible to attenuate the vibraiion by embebding MMA in the beam.

Magnetostrictive particulate actuators (MPAs) that take advantage of easy embedability and remote excitation capability of magnetostrictive particles are proposed as new actuators for smart structure applications. A MPA is configured as a small rectangular polymeric beam with magnetostrictive particles dispersed uniformly. Based on the compatibility condition, a load line equation is developed that relates the free strain with the mechanical stress experienced by the magnetostrictive particles. The load line equation and the magnetoelastic property of the material are used to develop a macroscopic behavior model of a MPA. Characterization experiments are used to find the orientation factor and pre-stress. Experimental work shows that the static performance of MPAs for an applied magnetic field depends on the volume fraction, orientation field, mechanical preload, and the stiffness of the polymeric matrix. In general this actuator can be used where the structure needs to be excited with a large force and small strain over a wide frequency range. For example, embedded in a laminated composite, MPAs can be used as micropositioners, vibration dampers, platform stabilizers, and motors.