Biomimetics
Yasaman Amiri,; Bahman Vahidi
Volume 15, Issue 2 , August 2021, , Pages 99-110
Abstract
Microneedles are a type of micron-sized needle that is the third most widely used delivery system after oral and injectable drug delivery, used in a variety of fields including drug release and rejuvenation. Optimizing the geometry of microneedles to reduce pain and inflammation has been important in ...
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Microneedles are a type of micron-sized needle that is the third most widely used delivery system after oral and injectable drug delivery, used in a variety of fields including drug release and rejuvenation. Optimizing the geometry of microneedles to reduce pain and inflammation has been important in recent years. Due to the high cost of microneedle fabrication, numerical simulation of microneedle penetration into the skin can be useful to evaluate the microneedle strength as well as its effect on the skin during penetration. In this study, first a new simulation method in Abaqus software with explicit method using cohesive elements to investigate the penetration of microneedles in the skin of the human forearm was presented. The skin was considered as Ogden and bilayer hyperelastic models. The microneedle was considered as a rigid body and a constant velocity of 0.6 mm/s was applied to it .The microneedle with bulk with bio-inspired titles was examined and its important parameters such as height, sharpness and bulk angle were evaluated. Finally, some proposed models of microneedles with longitudinal grooves are presented to increase the concentration of stress on the skin and prevent friction. A comparison of the designed microneedle with the barbless microneedle shows that the barbed microneedle concentrates more than twice as much stress on the skin, but reduces the penetration force by as much as 15%, making it easier to penetrate the skin. The results show that the reduction longitudinal grooves increase the tension created in the skin by about 10%, but have little effect on the penetrating force on the skin.
Biomimetics
Hiwa Sufikarimi; Karim Mohammadi
Volume 11, Issue 4 , February 2018, , Pages 337-349
Abstract
In this paper, we tried to present a robust and reliable approach to object recognition by inspiring human visual system. A famous model, inspiring mammalian visual system, is HMAX (Hierarchical Model and X). It shows significant accuracy rates on object recognition tasks. However, there are some differences ...
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In this paper, we tried to present a robust and reliable approach to object recognition by inspiring human visual system. A famous model, inspiring mammalian visual system, is HMAX (Hierarchical Model and X). It shows significant accuracy rates on object recognition tasks. However, there are some differences between this model and human visual system. Indeed cortex's functions are not properly modeled. Unrepeatability under fixed conditions, redundancy, high computing load and being slow are some drawbacks of HMAX. By modeling the secondary visual cortex and adding to the HMAX, we tried to introduce a more accurate model of the human visual system and cover the drawbacks of the previous models. The proposed approach functionally mimics the secondary visual cortex. Attending to high-level features, selecting discriminative and repeatable features, it has higher performance than standard HMAX. The added parts have negligible computation load. Therefore, it does not slow down this model. On the contrary, by selecting brief and useful features, the speed of the model is increased. The proposed approach is compared to the standard HMAX in terms of speed and accuracy rate. The results showed the advantage of proposed approach rather than the standard HMAX. In addition, the effect of the number of features and training images on their performance was shown. It is shown that the proposed approach has a better performance than the standard HMAX especially when the number of feature and training images is small.
Biomimetics
Mohammad Reza Nikmaneshi; Bahar Firoozabadi; Mohammad Saeid Saeidi
Volume 7, Issue 2 , June 2013, , Pages 97-105
Abstract
The front part of a cell is divided to two regions called lamellum and lamellipodium (lamellipodial). Internal flows in this part plays an essential role for cell migration. Indeed, there are many protein filaments called actin in lamellum and lamellipodium, which induce the cell motion with polymerization ...
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The front part of a cell is divided to two regions called lamellum and lamellipodium (lamellipodial). Internal flows in this part plays an essential role for cell migration. Indeed, there are many protein filaments called actin in lamellum and lamellipodium, which induce the cell motion with polymerization in the leading edge of the cell. The actin filaments adhere to the extracellular matrix (ECM) by means of focal adhesions and they have contact by myosin motor proteins. The myosin motor proteins cause actin retrograde and anterograde flow exerted contractile stress on them. The focal adhesions exert frictional stress on the actin filaments. In this work, we developed a two-dimensional continuum model of the fanshaped lamellipodial to obtain the actin retrograde flow. In addition, the actin filaments are assumed as a highly viscous Newtonian fluid. We also investigated the effects of the myosin distribution and cell speed on the actin flow. Our results include actin flow and myosin distribution in the moving cell, and we also illustrate their relation together. These results accord to reported experimentally and numerically data, and are verified with them.
Biomimetics
Behzad Seyfi; Hosein Mansourinejad; Bahman Vahidi; Nasser Fatouraee
Volume 6, Issue 3 , June 2012, , Pages 169-175
Abstract
Peristaltic flow is one of the important mechanisms of fluid transmission. In addition to the divers engineering applications, this mechanism plays an important role in biological organs such as digestion system and urine excretion. In this paper, urine bolus transportation in ureter has been investigated ...
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Peristaltic flow is one of the important mechanisms of fluid transmission. In addition to the divers engineering applications, this mechanism plays an important role in biological organs such as digestion system and urine excretion. In this paper, urine bolus transportation in ureter has been investigated experimentally using a peristaltic flow simulator apparatus. Some of the features of this apparatus worth mentioning are its ability to use it to investigate the influence of some important parameters in peristaltic flow, such as the effect of pressure difference between the kidney and the bladder on the quantity of discharge and reflux rates, effect of the mean velocity of bolus transport on discharge rate, existence of fluid film and its effect on bolus discharge rate, and effect of fluid bolus length on reflux rate. Then we compare the obtained results with the similar theoretical studies. It was observed that an increase in the pressure difference between inlet and outlet decreases the ratio of reflux to initial volume of the bolus, and it increases the discharge rate. Moreover, the quantities of reflux and discharge rate decrease by decreasing the bolus transport velocity. It was also observed that the thickness of the fluid film has an inverse relation with respect to the discharge rate and with increasing the bolus length reflux is increasing.
Biomimetics
Saeed Rashidi; Seyed Mohammad Reza Hashemi Golpayegani; Ali Fallah; Farzad Towhidkhah
Volume 4, Issue 1 , June 2010, , Pages 33-44
Abstract
In drawing movements, the constraints imposed on the trajectory geometry properties and kinematics are known with two laws: 2/3 power law and isochrony phenomenon. In this paper experiments have been designed to study the relation between two empirical laws in straight and curved patterns of drawing ...
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In drawing movements, the constraints imposed on the trajectory geometry properties and kinematics are known with two laws: 2/3 power law and isochrony phenomenon. In this paper experiments have been designed to study the relation between two empirical laws in straight and curved patterns of drawing movements in 16-18 years old subjects. Providing two models of power is indicated that in drawing movements, invariant features can be defining. These features are independent of subject, direction and size of trajectory and together they can simplify the role of the upper motor control system and decrease the degrees of freedom and the computational complexity.
