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In order to improve the living standards of diabetes patients and reduce the negative health effects of this disease, the medical community has been actively searching for more effective treatments. In recent years, an artificial pancreas has emerged as an important approach to managing diabetes. Despite these recent advances, meeting the requirements for miniaturized size, accurate sensing and large-volume pumping capability remains a great challenge. Here, we present a novel miniaturized artificial pancreas based on a long microtube sensor integrated with an ultrasonic pump. Our device meets the requirements of achieving both accurate sensing and high pumping capacity. The artificial pancreas is constructed based on a long microtube that is low cost, painless and simple to operate, where the exterior of the microtube is fabricated as a glucose sensor for detecting diabetes and the interior of the microtube is used as a channel for delivering insulin through an ultrasonic pump. This work successfully achieved closed-loop control of blood glucose and treatment of diabetes in rats. It is expected that this work can open up new methodologies for the development of microsystems, and advance the management approach for diabetes patients. [Display omitted] • We report a miniature artificial pancreas with accuracy and high pumping capacity. • The artificial pancreas is based on a long microtube sensor and an ultrasonic pump. • This work realized a closed-loop control of blood glucose levels in diabetic rats. [ABSTRACT FROM AUTHOR]

Currently, pumps are used in various fields to supply air and liquid. These pumps include sliding parts and there is a limit of life time due to friction and wear. To solve this problem, a number of pumps using ultrasonic vibration have been proposed. A common feature of ultrasonic pumps is having no sliding parts. Therefore, the life time seems longer than those of the conventional pumps. In the present study, we found an occurrence of pump effect when an opposing block faces ultrasonically vibrating surface with a small gap. The ultrasonic transducer has a hole to provide the path for fluid flow and the opposing surface was a tapered end of an aluminum cylinder. According to the measurement results of gauge pressure, when circumference of the opposing block is tapered, air was discharged from the gap of two surfaces. On the other hand, when center of the block is tapered, air was sucked into the gap. Microscopic quasi-static behavior of the two surfaces is observed by using a digital microscope during pump operation.

Characteristics of an ultrasonic suction pump that uses a vibrating piston surface and a pipe are numerically simulated and compared with experimental results. Fluid analysis based on the finite-difference time-domain (FDTD) routine is performed, where the nonlinear term and the moving fluid–surface boundary condition are considered. As a result, the suction mechanism of the pump is found to be similar to that of a check valve, where the gap is open during the inflow phase, and it is nearly closed during the outflow phase. The effects of Reynolds number, vibration amplitude and gap thickness on the pump performance are analyzed. The calculated result is in good agreement with the previously measured results. [ABSTRACT FROM AUTHOR]

An ultrasonic suction pump for condensate return is characterized and successfully applied to a heat pipe cooled ultrasonic horn operating at 20 kHz. The suction pump is tested at atmospheric and for the first time at heat pipe conditions, i.e. near vapour pressure. Pump characteristic near vapour pressure differs remarkably from that observed under atmospheric conditions. The optimal gap size between pipe and vibrating surface is bigger at vapour pressure and it is less sensitive to gap size adjustments., (Copyright © 2018 Elsevier B.V. All rights reserved.)