Development of crystallographic process technology for piezoelectric actuator for bio-mems device

Recently, the lead free piezoelectric material, which could be used for the actuator and the sensor of medical care devices, such as the health monitoring system (HMS) and the drug delivery system (DDS), is strongly required. In this study, we try to find a new biocompatible and lead-free piezoelectric material, by using the three-scale processcrystallographic analyses scheme, which consists of the first-principles calculations, the homogenization based finite element method, and the process optimization algorithm. After numerical calculations, we found an optimum biocompatible element combination and a tetragonal crystal structure of candidate material MgSiO3. As a result of process crystallography simulation to adjust with the selected substrate Au(111), lattice parameters of MgSiO3 with tetragonal structure were obtained as a=b=0.3449nm and c=0.3538nm, and its aspect ratio was 1.026. The piezoelectric stress constants of a non constraint MgSiO3 crystal, e33=4.57C/m2, e31=-2.20C/m2 and e15=12.77C/m2, were obtained. Macro homogenized piezoelectric stress constants of MgSiO3 thin film were obtained as e33=5.10C/m2, e31=-3.65C/m2 and e15=3.24C/m2. We confirmed the availability of our process crystallographic simulation scheme for a new biocompatible piezoelectric material design through the comparison with the experimental observation of a newly generated MgSiO3 thin film material

Optimum design of magnetic field environment for axonal growth control in nerve cell regeneration process using electromagnetic field analyses

In this study, an optimum magnetic field environment for the nerve axonal extension and control of axonal growth direction in the nerve cell generation process was searched by using electromagnetic finite element analyses. Recently, the developments of 3D-scaffold structures employing biodegradable polymers have been an attracting attention for the clinical treatments of damaged nerve tissues. The magnetic stimulation is introduced to accelerate the regeneration speed of nerve axon inside the 3D-scaffold. According to experimental observation of Blackman, C.F. and his research group (1993) [1], it was found that 50 Hz AC magnetic field has promoted the regeneration of axonal extension in the case of pheochromocytoma cells (PC12). They identified the optimum configuration of the coil and the threshold value of driving current for the initiation of PC12 axon growth. However, they did not evaluate analytically the magnetic flux density and the magnetic field in the cell culture liquid for the PC12 axon growth initiation. Therefore, at first we employed the electromagnetic finite element analyses (FEA) to evaluate the magnetic flux density in the case of Blackman’s experiment. Simultaneously, we identified the relative magnetic permeability of Dulbecco’s Modified Eagle Medium (DMEM) as 1.01 at 50 Hz. Finally, we obtained the value of magnetic flux density inside DMEM as 4.2 T. Next, we try to design the configuration of Helmholtz coil, which can generate an optimum magnetic field to stimulate most effectively for PC12 axon extension. It is confirmed that the magnetic field gradient affect the extensional speed of PC12 axon, which can be achieved by setup the one peripheral coil and two coils at the center. We found an optimum configuration of Helmholtz coil to generate the magnetic field environment and fabricate an experimental bioreactor for PC12 cell culture. We examined the effectiveness of magnetic stimulation for PC12 nerve axon’s extension quantitatively. Further, we try to find the relationship between the magnetic field gradient and the direction of nerve axon’s extension

Bending and springback prediction method based on multi-scale finite element analyses for high bendability and low springback sheet generation

In this study, a sheet bendability and springback property evaluation technology through bending test simulations is newly developed using our multi-scale finite element analysis code, which is based on the crystallographic homogenization method

Distribution and protective function of pituitary adenylate cyclase-activating polypeptide in the retina

Pituitary adenylate cyclase-activating polypeptide (PACAP), which is found in 27- or 38-amino acid forms, belongs to the VIP/glucagon/secretin family. PACAP and its three receptor subtypes are expressed in neural tissues, with PACAP known to exert a protective effect against several types of neural damage. The retina is considered to be part of the central nervous system, and retinopathy is a common cause of profound and intractable loss of vision. This review will examine the expression and morphological distribution of PACAP and its receptors in the retina, and will summarize the current state of knowledge regarding the protective effect of PACAP against different kinds of retinal damage, such as that identified in association with diabetes, ultraviolet light, hypoxia, optic nerve transection, and toxins. This article will also address PACAP-mediated protective pathways involving retinal glial cells