Intravenous (IV) fluid therapy is a common medical practice that is widespread worldwide, and the method has remained unchanged for more than a century.The IV bag is suspended from an IV stand or pole, and the pressure created by gravity is used to administer the drug.However, this method inevitably reduces the mobility of patients, and may cause accidents such as falls during movement.To solve these problems faced in home care, nursing home, and hospital settings, this study aims to develop a non-hanging, non-electric-powered IV infusion pump with reasonable portability and operability.In this study, instead of gravity, atmospheric pressure is used as the driving force.The infusion device developed is required to achieve a certain level of dosing stability and accuracy, in line with medical guidelines and ideally as comparable to the existing gravity method.We developed a number of prototypes based on different pressurization mechanisms using vacuum piston cylinders as the driving source in order to find an optimum mechanism capable to produce a stable flow rate comparable to the suspended drip system.Tests on performance in terms of discharged flow rate were conducted on three feasible prototypes based on three different pressurization mechanisms, using a gravimetric test bench built for this purpose.The tests show that the pressurization mechanism using an inflating air bag to compress a drip bag has the best performance in terms of flow rate stability.
We measured the temperature dependencies of resistivity, Seebeck coefficient, magnetoresistivity, and Hall coefficient from 20 to 300 K for an individual single-crystal bismuth wire with a diameter of 1.90 μm and a length of 1554 μm. The wire was embedded in a quartz glass after making local electrodes on the wire through a nanofabrication process. The temperature dependencies were investigated using a model that considered not only the wire diameter, crystal orientation, band structure, and Fermi surface of the bismuth, but also the scattering process and mean free path of the carrier. We were able to explain the dependencies of resistivity and Seebeck coefficient on the contribution of each carrier pocket for the bismuth wire. The results showed that the specific conductivity of the carrier pocket of bismuth was dominant in the lower temperature region due to the wire geometry. As a result, the characteristic temperature dependence of resistivity was observed. Furthermore, the temperature dependence of the Hall coefficient was estimated using conductivity, and the data indicated that the experimental and calculation results were in good agreement.
