Deformable Chambers Research Articles

Optimization of the forming sequence of a threaded insert with groves by means of FEM simulation

In this paper the forging sequence of a new type of threaded insert is investigated by means of FEM simulations and subsequently optimized in order to decrease the number of operation. In fact, if the standard forging sequence of inserts without groves is used, an external heat treatment is usually realized after the product forming thus requiring a further forging operation after the H.T. for grooves formation. A new manufacturing sequence is here proposed and investigated: five forming operations including groves forging are sequentially realized then the complete annealing is realized at the end of the cycle. FEM simulation showed that the material hardening during groove formation strongly influenced the insert deformation during fastening and, in order to shift the annealing treatment at the end of the sequence, the shape of the deformation chamber needs relevant geometry modification. A FEM campaign was therefore performed in order to analyze the behaviour of the insert during the fastening phase on different sheets thickness, following different possible forging sequences. A pre-series of the developed inserts following the optimized sequence is then produced and tested: the grooved inserts properly fastened the required sheets range and the shape of the deformed inserts accurately matched the simulated geometry.

Lab-on-a-Foil: microfluidics on thin and flexible films

This critical review is motivated by an increasing interest of the microfluidics community in developing complete Lab-on-a-Chip solutions based on thin and flexible films (Lab-on-a-Foil). Those implementations benefit from a broad range of fabrication methods that are partly adopted from well-established macroscale processes or are completely new and promising. In addition, thin and flexible foils enable various features like low thermal resistance for efficient thermocycling or integration of easily deformable chambers paving the way for new means of on-chip reagent storage or fluid transport. From an economical perspective, Lab-on-a-Foil systems are characterised by low material consumption and often low-cost materials which are attractive for cost-effective high-volume fabrication of self-contained disposable chips. The first part of this review focuses on available materials, fabrication processes and approaches for integration of microfluidic functions including liquid control and transport as well as storage and release of reagents. In the second part, an analysis of the state of Lab-on-a-Foil applications is provided with a special focus on nucleic acid analysis, immunoassays, cell-based assays and home care testing. We conclude that the Lab-on-a-Foil approach is very versatile and significantly expands the toolbox for the development of Lab-on-a-Chip solutions.

Device capable of being submerged and including an acoustic transducer

A case (2) in which an acoustic transducer (22) is mounted so as to communicate in a watertight manner with the exterior of the case (2) via acoustic energy. The transducer (22) is attached to a membrane (17) separating it in a watertight manner from an inlet cavity (10, 11) which is arranged in the case (2) and is in direct communication with the exterior. The membrane (17) is resiliently applied by its periphery onto a rest surface (12) arranged around the cavity separating the latter in a watertight manner from a deformation chamber (13) situated on the side of the membrane (17) opposite to the inlet cavity while being in communication with the interior of the case. The bottom (13a) of the deformation chamber (13) forms a support surface for said membrane (17) when external static pressure greater than a predetermined value is applied thereto.

Characteristics and fabrication of NiTi/Si diaphragm micropump

A novel micropump actuated by NiTi/Si composite diaphragm was described in this paper. The driving principle, microfabrication processes and characteristics of the pump were reported. The pump is composed of a deformable chamber and two silicon flap check valves. The outer dimension of the pump is 6 mm×6 mm×1.5 mm , with the diaphragm size of 3 mm×3 mm×20 μm. The fabrication processes include silicon micromachining and AuSi eutectic bonding. By using the recoverable force of NiTi thin-film and biasing force of silicon membrane, the actuation diaphragm realized reciprocating motion effectively. Experimental results show that the pump has superior performance, such as high pumping yield (up to 340 μl/min), high working frequency (up to 100 Hz), and long fatigue life time (more than 4×10 7 working cycles).

Shock absorbing devices using rheopexic fluid

Shock absorbing devices utilize rheopexic fluid contained in a deformable sealed chamber which is subjected to external shock forces. Upon application of the shock forces to the deformable sealed chamber, the rheopexic fluid filled therein is exerted with shear stress which causes the rheopexic fluid to increase its consistency and shock absorbent characteristics as a function of increasing shear stresses applied thereto. Additionally, when used in an application wherein the device is placed against a body part of a user, the rheopexic material "molds" itself to the body portion of the user. When left at rest, the rheopexic material returns to its initial fluid, low-consistency state.

Effects of pressure on contact dermatitis.

In human volunteers, firm pressure was applied to deformable plastic chambers containing chemical irritants, glass fibers, and selected allergens to which the subjects were sensitive. Pressure variably intensified irritant dermatitis and strikingly enhanced fiberglass dermatitis. Pressure did not influence allergic contact dermatitis. Pressure is one of several mechanical factors that can aggravate nonallergic contact dermatitis.