Developing a new concentration technique of virus, which is continuous, quick, easy, mobile, and low cost and energy, is one of the key issue to realize high-sensitive virus sensing to prevent infectious diseases. In this work, we proposed and experimentally demonstrated a concentration device for virus using ion depletion zone generated by ion concentration polarization. The performance of the method was evaluated by using fluorescent nano-particles, baculovirus, albumin, and dextran. As the result, all the samples were successfully concentrated by the proposed method. We also found that the area of ion depletion zone was controlled by flow rate and applied voltage, which may leads not only concentration but also separation by creating a network of ion depletion zones, in the future.
In this study, we report on a wearable blood pressure measurement device using cuffless measurement methods. Our device comprises a wrist band device for the arterial tonometry method and a ring device for the photoplethysmography method. Blood pressure was calculated from the pulse transit time between the ring device and wristband device. Furthermore, we compared the accuracy of blood pressure measured by the arterial tonometry method and that calculated from the pulse transit time and multiple regression equation. The correlation coefficient of the tonometry method was improved from 0.90 to 0.99 using the combination of both cuffless blood pressure measurement methods.
In this study, we proposed a thickness estimation method of tumor using a grasping forceps with sensors and evaluated the method by estimating the thickness of tumor models located in tissue models. Though palpation is an important technique for distinguishing a tumor, the palpation during thoracoscopic surgery is difficult because of the lack of tactile sense. In order to compensate the surgeon's tactile sense, we developed a forceps with two MEMS (Micro Electro Mechanical Systems) triaxial tactile sensors. By using this forceps, we proposed a tumor thickness estimation method focusing on the detected force difference according to the hardness of the grasping area. Then, we evaluated the thickness of tumor models located in the soft tissue models to prove the feasibility of our estimation method. The 5 mm and 10 mm diameter spherical tumor models located in the tissue models were estimated 3.3 mm and 10.7 mm, respectively. This result indicates the possibility that the proposed method enables to estimate the thickness of a tumor within an organ.
Kinesin is a class of motor protein which moves on microtubules in eukaryotic cells. Because of its size and ability to convert ATP hydrolysis to mechanical force, engineering applications using kinesin as a novel power source in a nano-micro fluidic device have been of interest to wide range of researchers in nano-bio-technology field. However, the active transport driven by kinesins has not been well focused in conventional experiments. It is mainly caused by the fact that diffusional transport is also incorporated into the measurement of molecular transport in a conventional flow cell, which has 103-fold larger dimensions than that of molecules used in the kinesin-microtubule assay. In this paper, we designed a pneumatically-driven microfluidic device that confines the kinesin motility assay in channels, whose dimension is 2-µm wide and 1-µm height, for the evaluation of active transport by kinesin. Microtubules were successfully immobilized in channels and kinesin-driven transport of quantum dots (QDs) was observed. We measured the mass flux in microchannels by the active transport to compare a flux by diffusion at a given concentration gradient. We found that the kinesin-driven active transport was dominant at a concentration gradient lower than 10 nM/50 µm and comparable to axonal transport reported in vivo. These results are important knowledge toward the development of functional device driven by kinesin and in vitro axonal transport models.
This paper reports a method to focus sound from a moving source in liquid to a fixed acoustic sensor using a varifocal acoustic mirror made from silicone rubber. A boundary between silicone rubber and air works as an acoustic mirror whose curvature radius can be changed. Simulation results showed that the spherical surface was able to focus sound coming from a point source to a certain point. It was confirmed that a fabricated varifocal acoustic mirror improved the ouptut of an acoustic sensor for different sound source positions. The curvature radius of the acoustic mirror corresponding to the maximum sensor output conformed to the value calculated using a theoretical equation. The sound pressure where the sensor was positioned became at most 12 times larger than that without the acoustic mirror.
This paper describes a hydrogel microspring formed by using a bevel-tip capillary and its application for a soft actuator. The hydrogel microspring was formed by extruding sodium alginate pre-gel solution into calcium chloride solution using a bevel-tip microfluidic capillary. We conducted experiments of changing relevant parameters such as flow velocity, tip angle of bevel-tip capillary and diameter of capillary. Based on those results, we suggest a model of the microspring formation. As an application of soft actuators, we encapsulated magnetic nanoparticles inside a hydrogel microspring and successfully actuated the microspring by applying magnetic field. We believe that our hydrogel microsprings could be used for various applications including actuators, sensors and scaffolds for cells.
We develop 2D asymmetric micromirrors with high vibration transmissibility for a glass-like retinal display according to the National Television System Committee standard via dynamic analysis using a single external piezoelectric ceramic vibrating element. The high-speed axis can attain a relatively much larger rotation angle by the addition of translational motion that is equal to the resonant frequency directly transmitted by the low-speed axis of a rotation oscillation system. Moreover, we fabricate 2D asymmetric silicon micromirrors using a silicon-on-insulator microelectromechanical system process and obtain 70.5-Hz and 19510-Hz resonant frequencies along the low- and high-speed axes, respectively. Furthermore, we measure the scanning range on a Lissajous pattern using a scale; the scanning angles are 12.4° along the low-speed axis and 23.7° along the high-speed axis.
Effect of annealing on magnetostriction of sputtered Fe60Pd40 film was evaluated using MEMS cantilevers with multi-layer structure of FePd (2 µm) / SiO2 (0.1 µm) / Si (50 µm). Magnetostrictive effect, which was about 45 ppm before annealing, increased 1.5-3 times after annealing at 350-450℃ for 30 min. In contrast, magnetostriction along the cantilever was lost when annealing at 500℃. The FePd film surface was highly oriented to fct <111)> and fcc <111> planes. In addition to the <111> orientation, in-plane crystal phase was oriented to fct <220> and fcc <220> planes. After annealing, surface orientated fct <111> plane increased with icreaseing annealing temperature, in spite of the magnetostoriction loss at 500℃, indicating that the fct <111> orientation has no effect on magnetostriction. In-plane fct <220> plane crystallization advanced by 400℃ annealing, and the orientation to fct <220> decreased by 500℃annealing, which were same tendency of the increase and decrease of the magnetstriction.
The 17×17 parallel electron beam lithography system has been implemented and evaluated to clarify its system problems and to accelerate a 100×100 massive parallel electron beam direct draw system under development. This paper describes its system concept, an electron emitter driver circuit, its control system and an exposure result.
In this paper, we design, fabricate, and evaluate Octagonal nMOSFET stress sensor for 8 direction stress detection. In previous works, stress detection device or devices, such as resistor and etc., have to be reattached along stress direction for measurement, because most of the stress sensors can detect only one dimension. However, this device is not necessary to reattach because this device has radial eight direction output terminals. As the results, we can realize that it is able to detect 8 dimensional stress directions.