Biomedical Engineering: Applications, Basis and Communications

The peak stress, the weight bearing area and the stress distribution of the articular contact at the human hip joint is the most important factors, which determine the location of the degenerative foci that later result in degenerative damage and in the development of osteoarthritis. In the paper, a ball-socket articular elastic contact modelling of the human hip joint is successfully established. This modelling can be used to predict the peak stress, the weight bearing area and the stress distributions of the articular contact at the human hip joint. In order to verify the validation of current modelling, an example is examined. The results show that the predictions from the current modelling are basically agreement with those reported in literatures. This shows the validity of the current modelling.

Positron emission tomography (PET) images can be used to judge whether or not a person's bodily tissue is showing abnormal metabolism, providing a tool for early diagnosis and treatment of illnesses. Contemporary PET scanners have retracted their septa in order to increase the collected coincidental events. Thus, the protocol either needs to undergo three-dimensional image reconstruction, or use rebinning formulas to perform the less expensive two-dimensional image reconstruction for final images. Reconstruction using the second method saves image reconstruction time. The main goal of the paper is to further improve the performance by overlapping the rebinning and two-dimensional reconstruction operations, so as to early start in reconstruction, and to be able to undergo image reconstruction based on the pipelined direct sinograms. Frequency distance relations are analyzed in detail to generate the Fourier transformed sinograms in order for subsequent pipelined stages of reconstruction. The two-dimensional reconstruction operation does not have to wait until the completion of all sinogram generations, therefore it can hide most of the time spent in rebinning operations. The associated parameters can be pre-calculated indiscriminately beforehand for best performance.

Rubber tiles are popular in playgrounds as protective surfacing to reduce the incidence of head injuries caused by children falling from equipment. However, Taiwan has not yet established a test code for assessment of the shock-absorption properties of such surfacing. For this study, an experimental model was established to evaluate the behavior of various rubber tiles. A hemispherical headform was dropped from a set height to strike the center of the specimen tile. The peak acceleration and Head Injury Criterion (HIC) were measured to assess the impact absorption of and critical height for a given rubber tile. The results show that utilization of the HIC index provides a more conservative assessment of the shock absorption and, ultimately, protection from head injuries than peak acceleration. The maximum critical heights of the rubber tiles used in this study for tile thicknesses of 45, 60 and 80 mm were 1.6, 2.0 and 2.2 m, respectively. Two-part rubber tiles with a base structure consisting of a box-like core offer superior protection from head injuries relative to analogous cylindrical, square pillar and solid structures. The maximum differences in peakacceleration and HIC values comparing the box-like core and solid structures at a thickness of 45 mm were 21% and 44%, respectively. The results of this study suggest a minimum of rubber thickness of 60 mm, based on probable maximum fall heights of more than 1.6 m. Moreover, incorporation of an appropriate cushioning structure in the base of the rubber tile could further improve protection.

Arterial compliance is defined as the variation of arterial vessel diameter under the blood pressure. This paper introduces the architecture of a brand-new compliance measurement. Two techniques are used: one is to use pressure feedback control and then obtain the variation of arterial vessel diameter at wrist; the other is to detect the delay time between two adjacent pressures and then calculate the downstream blood pressure according to the upstream blood pressure and delay time. The above information can easily compute the dynamic nonlinear arterial compliance. Therefore, the instrument comprises of two pressure sensors: one is fixed and the other is sliding upward and downward by a peizo-actuator. The piezo-actuator is imposed a strain gauge which senses the displacement of the actuator, or the variation of arterial vessel diameter. The design philosophy and fabrication of this instrument are present.

In this research, a tiny size non-invasive pressure detection head is designed and fabricated. It serves as an essential component of the multi-functional sphygmus detection system. When the pressure detection head places upon the correct position at wrist, it transmits the pulse pressure from the touch membrance through the silicon oil, and then to the pressure die. This kind of structure will provide a stable data acquisition for pulse pressure sensing. To verify the performances of the pressure detection head, a pressure test bench together with standard testing procedure is developed to gather information on the tested signals. The test results indicate that the designed pressure detection head is feasible and can be used for sphygmic diagnosis in medicine.

Chitosan membranes were prepared by a thermal induced phase separation method, following treatment with nontoxic NaOH gelating and Na₅P₃O₁₀, Na₅SO₃ crosslinking agents. Effects of these reaction agents on chitosan membranes were evaluated to survey the feasibility of using these membranes in guided tissue regeneration (GTR) application. The preliminary results showed chitosan membranes crosslinked with Na₅P₃O₁₀ and Na₂SO₃ had gel content of 53.5% and 52.2%r, respectively. Contrarily, the chitosan matrix gelated with NaOH dissolved completely during gel content measurement. Chitosan membrane treated with Na₅P₃O₁₀ had lowest elastic modulus of 12.9 Mpa as compared with other membranes treated with Na₂SO₃ (17.9Mpa) and NaOH(23.6Mpa). From SEM observations, NaOH gelated chitosan membrane had the smoothest surface morphology than others. However, Na₅P₃O₁₀ crosslinked chitosan membrane had better cell adhesion and proliferation results in cell culture test. All three chitosan membranes degraded by about 23%∼28% of initial weight after a 90-day in vitro shaking test.

While there have been studies on the impact attenuation of different floor coverings, the effectiveness of using foam mattress as protective floor covering against geriatric hip fracture is still unknown. The objective of current study is to compare the force attenuation of foam mattress with that of teak wooden block when subjected to an impact force that the human hipbone would experience in accidental fall. A porcine hip fall simulator which consisted of a 12-kg impactor and a surrogate pelvis made by 8 month old porcine hipbone and with effective stiffness of 75 kN/m was set up to simulate sideways fall of human hip. The porcine hip fall simulator was allowed to drop freely on the surrogate pelvis from a height starting from 10 cm to a final height of 50 cm. The results showed the use of one piece and two pieces of foam mattress provided significant force reduction ranging from 21% to 37% and from 38% to 61% respectively when compared to wooden impact, and the optimal force reduction occurred when impact energy approached 18 to 24 joules. We found the foam mattress worked best only in those falls where the impact load was of relatively low energy. Relevance: Prevention of geriatric hip fracture is one of the major health issues in the foreseeable future. This study highlight the fact that the use of a protective floor covering may reduce the impact force on the hip in accidental fall and could be a relatively economical and practical way to reduce the risk of geriatric hip fracture.

In order to simulate the whole operation during inhalational anaesthesia, an intelligent architecture for the monitoring, control and modelling includes four blocks, which are a hierarchical structure for monitoring depth of anaesthesia (DOA), drug controller, patient model, and vaporizer model. In the first block, using the electroencephalograph (EEG) signals (i.e., bispectral index (BIS)), end-tidal anesthetic agents (Etaa) as the first level for primary DOA, and the systolic arterial pressure (SAP) and heart rate (HR) as the second level for secondary DOA, a hierarchical structure is therefore used to merge these two levels to decide DOA via fuzzy model. Block 2 is a drug controller that controls the drug infusion to the patient using a fuzzy logic controller. In the third block, a four-input and four-output neural network has been designed for patient model. Finally, in the fourth block, a single input and output neural network has also been designed for vaporizer model. Simulating the 13 clinical patients' status with different set points of DOA (defined from 0 ∼ 100), the average of drug consumptions of the anaesthetic gas is 0.93±0.26, 0.69+0.24, and 0.74 ± 0.21 % when setting the set point of DOA at 50 (i.e., anaesthetic ok), 30 (i.e., anaesthetic small deep), and 10 (i.e., anaesthetic deep), respectively. In comparison with the routine standard practice group (i.e., 0.69±0.30 %) using the same inhalational gas, there is a significant difference in DOA at 50 (p < 0.05) but no any significant differences in DOA at either 30 or 10 (p > 0.05). We conclude that the routine standard practice of clinical trials is always controlled DOA at 30 and 10 which are lesser drugs used than DOA at 50.