Multi-sample conditioning system
A multi-sample conditioning system may include a sample chamber for each sample or a sample chamber holding one or more samples. Multiple samples enable replication for statistical analysis and individual sample chambers enable individual nutrient flow profiles for each sample. A mechanical imbalance may be created when a sample chamber is removed or when samples of different stiffness are conditioned together. The mechanical imbalance may result in an undesired alteration of the desired conditioning profile and increase the variation in the conditioning profile applied to each sample. An asymmetric-loading support assembly provides a low friction support to reduce the undesired alteration of the desired conditioning profile applied to the samples and reduce unwanted reaction loads on the conditioning drive mechanisms. The asymmetric-loading support assembly preferably includes a flexure as the low-friction, high-stiffness support. Other examples that can provide low-friction, high-stiffness support include air bearings, magnetic bearings, and hydraulic bearings.
1. A system for applying mechanical stimulation to a plurality of samples, the system comprising:
a plurality of sample chambers, each having first and second sample grips therein;
a support structure for removably holding at least two of the sample chambers in fixed positions relative to an actuator;
a push-bar assembly having mechanical couplings, along a first axis, for transmitting force from the actuator to the first sample grips of as many sample chambers as are coupled to the support structure;
a reaction crossbar coupled to the support structure and having mechanical couplings for supporting the second sample grips of as many sample chambers as are coupled to the support structure;
a flexure mounted to the support structure, the flexure allowing motion in a first direction with low friction and having high-rigidity resisting motion in at least one second direction; and
a support rod having a linear axis, rigidly coupled at a first end to the push-bar assembly and coupled at a second end to the flexure;
the flexure, through the support rod, allowing motion of the push-bar assembly parallel to the linear axis of the support rod and resisting rotation of the push-bar assembly in a plane defined by the push-bar's first axis and the support rod's linear axis.
2. The system of claim 1 wherein the flexure controls motion of the push-bar assembly by allowing linear motion of the support rod along the support rod's linear axis and resisting lateral motion of the support rod.
3. The system of claim 1 wherein the flexure comprises a generally U-shaped band rigidly fixed to the support structure at first and second ends of the U-shape and fixed to the support rod at the center of the U-shape,
wherein the flexure is formed of a material remaining in an elastic region over an expected peak-to-peak axial displacement of the support rod while providing stiff resistance to lateral movement of the support rod.
4. The system of claim 1 further comprising:
a second support structure for removably holding at least two additional sample chambers in fixed positions relative to the actuator;
a second push-bar assembly having mechanical couplings, along a second axis, for transmitting force from the actuator to the first sample grips of as many sample chambers as are coupled to the second support structure;
a second flexure mounted to the first or second support structure, the second flexure, through the support rod, allowing motion of the second push-bar assembly parallel to the linear axis of the support rod and resisting rotation of the second push-bar assembly in a second plane defined by the second axis and the support rod's linear axis.