As shown by the schematic in Figure 1(a), the RBC is suspended in a microchannel shear flow by which a constant shear stress will be applied to the cell. In this case, the deformation degree of the RBC, in other words the shape of the RBC, will rely on the deformability of the cell. Considering then that the RBC shape is one of the first factors that influence the resistance and its distribution measured by the electrodes, this means that if the height position of RBC can be precisely controlled, the RBC deformability can be measured by analyzing the resistance and its time-series distribution.On the basis of these physical concepts, we have fabricated a microsensor consisting of a microchannel and electrodes [18]. Measurements were conducted upon two kinds of samples, normal human RBCs and glutaraldehyde-treated (rigidified) RBCs, to evaluate the feasibility of the sensor.
Further, the influence of the applied voltage frequency on the resistance of the RBC and electric double layer formed at the electrode surfaces were evaluated in order to specify the certain frequency that can effectively increase the sensor sensitivity. In this paper, we will first carry out numerical simulations of the electric field around the symmetric sensor electrodes when the RBC passes between them. The effects of the cell height position, channel height, and size of the electrodes are evaluated in order to provide some insight into the optimum shape of the sensor to be used in the experiment. The symmetric electrode-type sensor is then fabricated on the basis of the numerical results.
The performance of the sensor is evaluated experimentally by using samples of normal human RBCs and rigidified RBCs. In preparing the rigidified RBC, the Ca2+ concentration in the RBC is controlled by using an ionophore rather than using glutaraldehyde. This way enables us to rigidify the RBC under the condition similar to the one of the actual phenomena in vivo, and also to gradually control the deformability of the RBC. The behavior of the RBCs will be visualized simultaneously using a high-speed video camera. The results are then compared with those obtained by the electrical measurements to determine the relationship between the resistance distribution and the deformation rate of individual RBC, and the performance of the proposed sensor is evaluated.2.
?Numerical MethodsNumerical simulation was carried out Anacetrapib to evaluate the impedance characteristic
We present a personal navigation system (PNS) based on inertial measurement units (IMUs). A PNS is a device that computes its own position in indoor or outdoor terrains without inhibitor manufacture depending on external signals. Our system consists of a commercial off-the-shelf IMU placed on the back of the user, near the body center of gravity (COG), and wirelessly connected to a handheld processing unit.