Biomedical Engineering: Applications, Basis and Communications

Ion-channel current recordings based on an incubation type planar patch clamp were first reported in 2008, using HEK293 cells expressed with TRPV1 channels and capsaicin as ligand molecules. At first the success probability (number of devices which normally worked/total number of devices fabricated) was extremely low (several %). Several years later, we have succeeded in significantly decreasing the base line noise by using a salt-bridge-type Ag/AgCl electrode and successfully demonstrated the application of an incubation type planar patch clamp to ligand gated ion-channel biosensors and light gated ion-channel biosensors using HEK293 cells expressed with ChRWR. Furthermore, a spontaneous ion-channel current from a neuronal network was successfully observed by using a planar patch clamp chip, on which the neuronal network was occasionally formed with a soma of a neuron on a micro through-hole. Although the neuronal network was not controlled, this success shows the high potential of realizing a high throughput screening device on the basis of channel current measurements, which contain the most important information on network conditions.

Background: The result of a standard urinary dipstick from a patient with diabetes mellitus type 2 can be used to predict the estimated glomerular filtration rate (eGFR). We designed a multilayer perceptron (MLP) to investigate the possibility and optimal number of variables for the prediction. Methods: A total of 299 volunteers with diabetes mellitus type 2 were included. The blood and urine samples from volunteers were analyzed for blood sugar, glycated hemoglobin, serum creatinine, and urine chemistry. The urine chemistry was examined by a standard urinary dipstick. Volunteer age and gender and six test items of the dipstick were set as eight variables for this study. The eight variables were grouped and examined for the optimal combination. The eight variables from 232 of 299 volunteers were used to train an MLP for the optimal variables. The performance of trained MLP was validated by the data from 69 of 232 volunteers. Results: The optimal combination for variables was the six test items of the dipstick and volunteer age. The area under the curve (0.928), accuracy (0.879), sensitivity (0.83), and specificity (0.88) of the trained MLP were examined. Conclusions: The results demonstrate the eGFR prediction potential of the results of a urinary dipstick using this method.

Several factors such as instability, misalignment, mechanical fractures and poor quality of bone are some factors that strongly influence the deterioration of knee implants. After a total knee replacement (TKR), proximal tibial bone suffers a resorption due to stress-shielding caused by the implant. The formation of weakening bone zones and loss of bone is one of the most clinical concerns. Then, the study, modification and improving of the simulation methods to analyze implants is a subject of the most concern. Thus, this work is focused in the analyses of the influence of the geometry and inclination of the attaching pegs in the femoral component of knee implants. The aim is to evaluate the geometry of the implant stem to improve the stresses distribution and to increase the implant lifespan. Stresses distribution at the attaching pegs of the femoral component, by considering several combinations of diameters, lengths and inclinations, have been analyzed using finite element analysis (FEA). The analysis was conducted for the $D=8$mm, L $=$ 13 mm and $\theta$ $=$ 0${}^{\circ }$, in three different positions of the gait cycle. The variation of the geometry of the attaching pegs generated changes in the stresses distribution in bone. As the diameter increases, the stresses decrease in the femur. The medial areas of the implant appear to be the most likely regions to show bone resorption.

Determining the viscoelastic response of cervix at different displacement rates can provide sufficient information for the normal mechanical behavior of the tissue in assessment of cervical insufficiency. The objective of this study was to investigate the effect of displacement rate on viscoelastic properties of rat cervix. Different displacement rates were employed to measure the tensile and load-relaxation properties of cervices from virgin and 16 days post-conception pregnant rats. After preconditioning, the displacement of 2mm was applied to the distal halves of five pregnant rat’s cervices and 1 millimeter to the five virgin samples circumferentially. Uniaxial tension tests were employed at the displacement rates of 0.01, 0.1 and 1 mm/s randomly and were held for 10 min while the tissues were relaxed. Tensile and load-relaxation curves were well described by a quasi-linear viscoelastic model. Statistical analysis revealed significant correlation between the change in displacement rate and the elastic response, as well as the viscous response of the virgin samples. For pregnant samples, though, the correlation was found significant between the displacement rate and the elastic response of the tissue. Virgin tissue is strongly viscoelastic. Quantitative measurements of cervical mechanical properties will lead to a more accurate assessment of cervical insufficiency and prediction of preterm birth.

A linear mathematical modeling of half-value layer measurements for X-ray equipment is discussed. The consistency check shows that a linear model is consistent with the value of an exponential model, provided that the thickness of the aluminum absorber used in the calculations is close to 2.5mm. To validate the linear model, a methodology for determining the half-value layer in conventional X-ray equipment was introduced. The study was based on the measurement of only two exposure values, with and without aluminum absorber, using lithium fluoride thermoluminescent dosimeters (TLD-100). The corresponding description through a straight line is given. Aluminum absorber of 2.40mm thickness was used in the measurements in 11 X-ray equipment. A Pearson statistical analysis used to determine the correlation between data obtained with an ionization chamber and TLD-100 provided a statistically significant $r=0.812$ and p-value $=$ 0.004.

The degeneration of sensory and motor systems due to aging could affect the elderly’s posture and increase the risk of falling. The strategies applied to maintain postural stability might be different between ages, especially in the condition requiring both proprioception and vision sensorimotor coupling. This study proposed a novel sensorimotor assessment protocol to evaluate the postural control ability across the aging process, by using the computerized dynamic posturography and the virtual reality (VR) system. Ten young and 20 elderly healthy adults without fall experience were recruited, and were assessed on a continuous-perturbed platform with or without the VR-based visual interference in a random sequence. Measured variables of the center of pressure as well as the weight-bearing ratio were analyzed and compared. Results showed that the postural sway was significantly larger in all subjects under the VR condition, but the young subjects could rapidly adjust the body to regain postural stability in a rhythmic and symmetric manner; whereas, the elderly adults performed less effectively in postural response. We suggested that the application of the multiple sensation disturbances with VR could effectively evaluate the postural control ability among the healthy elderly. The proposed assessing protocol is also recommended for training the sensorimotor integration to improve the dynamic postural control ability.

Electrocardiography is a non-invasive medical diagnostic procedure used to record the electrical activity of the heart as a waveform. An electrocardiogram (ECG) can be utilized to evaluate the electrical activity of the heart, also the rate and regularity of the heart beat and other related diagnoses. ECG systems have evolved along since its invention and researches are going on continuously to decrease the complexity of ECG systems. This paper discusses the designing of a single arm single lead ECG system to acquire ECG signals from areas of left arm alone. The proposed system uses pre-gelled disposable surface electrodes and dry copper electrodes. The single arm approach in ECG acquisition reduces the complexity of the system to a greater extent and also improves the ease of use and patient comfort. The paper discusses the various designing aspects and the working of the single arm single lead ECG system. A hardware only approach has been used here in the design of the ECG system. ECGs were obtained from 10 healthy subjects using the proposed system, which were compared along with ECG acquired from a commercially used system. The obtained ECG had morphological features similar to a normal ECG waveform. The results of the comparison were very promising and all the values recorded were in the normal range of values for the respective parameters in comparison.

The manufacturing of limb prosthesis socket that is comfortable for the amputee depends greatly on prosthetic practitioner’s knowledge of socket biomechanics and skill. It involves multistage manual corrections depending upon the clinical condition of the patient’s residual limb which may be affected by shrinkage or possible damage of plaster of paris (PoP) mold. The current work describes a novel process simplified through digitization, it integrates conventional PoP processes, reverse engineering (RE), and additive manufacturing (AM) technologies to design and develop a socket. The stereolithography (STL) file generated from the scan data was modeled on a fused deposition modeling (FDM) based AM. Its fitment was assessed with the help of INSPECTPLUS and GEOMAGIC reverse engineering tools. This approach takes the guess work out of prosthetic practitioner’s job, ensures better fitment, and shortens the total fabrication time leading to improved patient satisfaction. The proposed method is a part of the ongoing research and it will offer maximum comfort on demand to the patients through digitization.