IRONSperm swimming by rigid-body rotation versus transverse bending waves influenced by cell membrane charge

Cell membrane potential affects the electrostatic self-assembly of magnetizable nanoparticles around the flagellum of sperm cells, leading to the formation of biohybrid microrobots (i.e., IRONSperm) with various bending stiffness. Here we explain the influence of bull sperm cell membrane potential on the formation of two types of IRONSperm samples that are produced by electrostatic self-assembly. The first type is a proximal-coated soft body with nanoparticles concentrated on the head to maintain high flexibility of the flagellum and create a passively propagating transverse bending wave under the influence of an external rotating magnetic field. The second type is a rigid-body with nanoparticles approximately uniformly distributed along the length to provide arbitrary geometry that maintains a constant chiral shape and propel by rotation about its long axis. We present a magneto-elastohydrodynamic model to predict the swimming speed at low Reynolds number for rigid IRONSperm with arbitrary shapes, and show that decreasing the bending stiffness allows the model to capture the behavior of its soft counterpart. While the response of a rigid chiral IRONSperm is distinguished by a greater swimming speed with a smooth decay with frequency, the benefit of a soft flagellum in certain scenarios would present a much smaller range of frequencies for wireless actuation.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Bio-Electronic

Soft Bio-Microrobots: Toward Biomedical Applications

Soft bio-microrobots have the potential to execute complex tasks in unexpected and harsh environments of the human body due to their dexterity and flexibility. The architectural designs of soft bio-microrobots either replicate the motion of natural creatures or capitalize on their motility. Based on this design principle, biologically inspired microrobots that imitate the movements and functions of biological systems, such as starfish, bacteria, and sperm cells, as well as biohybrid microrobots that combine motile micro-organisms or cells with functional components have been developed. Herein, an overview of the design principles, energy sources, and biomedical applications of existing soft bio-microrobots is presented. It is shown that the incorporation of externally responsive material enables biologically inspired microrobots to change their shapes and imitate the motion of living organisms under external stimuli, and it is interpreted how biohybrid microrobots are guided through the tactic behavior of microorganisms or cells. Finally, perspectives on key challenges that soft bio-microrobots must overcome to achieve in vivo biomedical applications are given

Yüksek hassasiyetli montaj işlemleri için minyatür delta robot tasarımı, en iyilemesi ve denetimi

Bu makalede yüksek hassasiyetli montaj uygulamaları için minyatür delta robot tasarımı, en iyilemesi ve denetimi sunulmaktadır. Bu delta robot modüler bir mikro fabrika kavramının bir parçası olup esas olarak hızlı ve hassas al-bırak işlemlerini gerçekleştirecek bir manipülatör olarak kullanılacaktır. Robotun önceden belirlenmiş 40 mm3 kübik şekilli bir çalışma uzayı için gerekli olan kinematik parametrelerin elde edilmesi için kinematik analiz gerçekleştirilmiştir. En iyileme sürecinden elde edilen parametreler kullanılarak tasarım süreci gerçekleştirilmiş ve robot üretilmiştir. Tasarlanan gerekli elektronik aksam ile ve denetim algoritmasıyla tasarım testleri gerçekleştirilmiş ve ümit verici sonuçlar elde edilmiştir. Tasarımın iyileştirilmesine yönelik yapılacak çalışmalar belirtilmiş ve yeni bir tasarım üzerinde çalışılmaya başlanmıştır

Bundle formation of sperm: Influence of environmental factors

Cooperative behaviour of sperm is one of the mechanisms that plays a role in sperm competition. It has been observed in several species that spermatozoa interact with each other to form agglomerates or bundles. In this study, we investigate the effect of physical and biochemical factors that will most likely promote bundle formation in bull sperm. These factors include fluid viscosity, swim-up process, post-thaw incubation time and media additives which promote capacitation. While viscosity does not seem to influence the degree of sperm bundling, swim-up, post-thaw migration time and suppressed capacitation increase the occurrence of sperm bundles. This leads to the conclusion that sperm bundling is a result of hydrodynamic and adhesive interactions between the cells which occurs frequently during prolonged incubation times

Fleksibilni slijedni sustav s koncentriranim parametrima sa suzbijanjem vibracija korištenjem LQR-a bez senzora

This work attempts to achieve motion control along with vibration suppression of flexible systems by developing a sensorless closed loop LQR controller. Vibration suppression is used as a performance index that has to be minimized so that motion control is achieved with zero residual vibration. An estimation algorithm is combined with the regular LQR to develop sensorless motion and vibration controller that is capable of positioning multi degrees of freedom flexible system point of interest to a pre-specified target position with zero residual vibration. The validity of the proposed controller is verified experimentally by controlling a sensorless dynamical system with finite degrees of freedom through measurements taken from its actuator.U ovom radu opisan je fleksibilni slijedni sustav sa suzbijanjem vibracija upravljan LQR regulatorom u zatvorenom upravljačkom krugu bez senzora. Vibracije su korištene u težinskoj funkciji koja se minimizira s ciljem eliminiranja rezidualnih vibracija iz slijednog sustava. Kombinirajući algoritam estimacije s klasičnim LQRom, razvijen je regulator za upravljanje gibanjem i vibracijama bez korištenja senzora, koji je sposoban pozicionirati određenu točku fleksibilnog sustava s više stupnjeva slobode u predefiniranu željenu točku bez preostalih vibracija. Validacija predloženog regulatora provedena je eksperimentalno upravljajući dinamičkim sustavom s konačnim brojem stupnjeva slobode uz korištenje mjerenja s aktuatora