A novel micropump is proposed comprising a PMMA-based rotor, a circular PDMS micro-chamber, and a semi-circular PDMS microchannel connecting the inlet and outlet reservoirs as the rotor spins, a plug of sample fluid is trapped within the microchannel between neighboring blades of the rotor and is driven through the channel toward the outlet. Meanwhile, the rotors periodically compress and release the inlet and outlet regions of the microchannel. Thus, as the rotor turns, one plug of sample fluid is drawn into the microchannel as another is ejected into the outlet reservoir. In other words, a peristaltic pumping effect is achieved. It is shown that the flow rate in the proposed device can be controlled simply by adjusting the rotational velocity of the rotor. A maximum flow rate of 1.22 ml/min is obtained given de-ionized water as the working fluid and a rotational velocity of 232 rpm. Moreover, given the same rotational velocity, flow rates of 0.724 ml/min and 0.336 ml/min are obtained for salad oil and engine oil, respectively.
Abstract:In a previous study we provided analytical and experimental evidence that some materials are able to store entropy-flow, of which the heat-conduction behaves as standing waves in a bounded region small enough in practice. In this paper we continue to develop distributed control of heat conduction in these thermal-inductive materials. The control objective is to achieve subtle temperature distribution in space and simultaneously to suppress its transient overshoots in time. This technology concerns safe and accurate heating/cooling treatments in medical operations, polymer processing, and other prevailing modern day practices. Serving for distributed feedback, spatiotemporal μ / ∞ H control is developed by expansion of the conventional 1D-μ / ∞ H control to a 2D version. Therein 2D geometrical isomorphism is constructed with the Laplace-Galerkin transform, which extends the small-gain theorem into the mode-frequency domain, wherein 2D transfer-function controllers are synthesized with graphical methods. Finally, 2D digital-signal processing is programmed to implement 2D transfer-function controllers, possibly of spatial fractionorders, into DSP-engine embedded microcontrollers. OPEN ACCESSEntropy 2014, 16 4938
Titanium alloy & stainless steel are major materials for bone fracture fixation such as bone screws and plates in today's medical devices. However, the fixation devices made of metal not only have the risk of metal ion release to cause human allergies, but they also need to be removed by a second surgical operation making pain and the risk of the patient’s wound infection after the bone fracture healing. The biodegradable Polylactic Acid (PLA) bone screws & bone plates have the great advantage of not needing a second operation, but their insufficient strengths make them not be widely used in the current bone fracture fixation. In the study, we use PLA as the matrix and in-mod heat treatment with induction coils to increase the strength of bone screw & plate by improving crystallinity of material. Regarding ASTM F2502 “Standard Specification and Test Methods for Absorbable Plates and Screws for Internal Fixation Implants”, we measure bending loads of test pieces before and after in-mold heat treatment, and obtain the optimized process parameters by Taguchi method that will increase the bend load of PLA bone plates by 34.82%. These optimal parameters are the injection speed of 80 mm/s, the melt temperature of 205 °C, the heat treatment temperature of 110 °C and heat treatment time of 20 min.
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