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Concepts for in-vivo-like mechanical strain




Abstract: Different actuation strategies can be employed to create membrane stretching. Imitating stretch forces inside of a cell to support cell culture is typically needed, for instance, in lung-on-chip tissue cultures (breathing) or the heart-on-chip model (heartbeat) and gut-on-chip (peristaltic intestinal movement). We will briefly outline the most widely used and promising methods, including pneumatic actuation and electromagnetic, piezoelectric actuation, and dielectrophoretic actuators used in microfluidic organ-on-chip technology.

1. Introduction

The tissues and cells of the body of a human being are exposed to various types of forces. The forces are varied across long ranges. For example, cartilage and bones are subject to compressive load when we walk or move, and blood vessels are constantly subjected to shear stress caused by vascular flow and to cyclic strain caused by lung tissue or blood pressure. It is subjected to mechanical stress during breathing. Forces from mechanical sources play a crucial role in the function of cells and their regulation, both in healthy and pathological conditions.

Cells detect and respond to mechanical forces via mechanotransduction. Mechanotransduction is a process that typically involves complex biological signal cascades, which transform automated signals into physical signals. The extracellular matrix (ECM) relays many automated signals to cells. The ECM comprises a complex web composed of glycosaminoglycans, proteins and proteoglycans in which cells reside. The central part of the ECM is collagen; however, collagen composition varies based on the kind of tissue. The cells can sense mechanical forces by forming small adhesions which connect the cells’ cytoskeletons in the ECM. While our knowledge of mechanotransduction at the molecular and cellular level is not fully understood, however, we are aware that mechanotransduction is involved in essential cell functions, including development, gene induction protein synthesis, and cell death. Incorrect forces or dysfunctions in mechanotransduction can lead to various common illnesses like osteoporosis and fibrosis, asthma, hypertension and cancer. Understanding the fundamental mechanisms behind tissues and the progression of the disease is crucial in pursuing new treatment and diagnostic methods.

In the traditional, in vitro cell culture models used for testing drugs or disease models, the importance of the application of forces to cells is usually neglected. This is partly due to the practical difficulties of providing mechanical details to in vitro culture in a controlled fashion. Recent advances in microtechnology, nanofluidics and biomaterials have led to the creation of new instruments to expose cells to mechanical forces such as shear stress tension and strain on the substrate, as well as recording the cell’s responses.

Although various mechanical forces can be transmitted to cells by organ-on-chip technology, this article will concentrate on how similar mechanical tensile strain to that of in vivo can be generated in the laboratory. We review recent efforts to create advanced cell stretching platforms based on various actuation strategies and discuss their potential for organ-on-chip research.

2. What actuation techniques can recreate mechanical strains in-vivo

Traditional laboratory methods to cause cyclic or static strain on cells are micropipettes, magnetic and optical Tweezers, atomic force microscopes (AFM), and bendable micropillars. Thanks to advances in soft lithography and the latest microtechnology, membrane-based stretching devices quickly became popular. They are comprised of an elastic membrane, whether porous or not, which may be stretched out in a controlled way to cause strain on the substrate. Membranes are a common component in microfluidic devices for valves or actuators, like the widely utilized check valves. They are using the knowledge in membrane manufacturing and its integration into microfluidic systems. Several groups have developed sophisticated membrane-based cell stretching devices that produce unidirectional multi-directional or 3-dimensional strain profiles. The amount of strain in living cells varies depending on various factors, including the type of tissue, its age, the surrounding ECM, and other factors. In vitro studies, the desired strains tend to be around 0.1-10 per cent of linear elongation. More fantastic strains cause cells dying as was previously mentioned by Guenat and colleagues. (2018) Cross-comparison among various models can be challenging because the strain can be measured and presented in various ways, such as the linear strain model, deformation of surfaces, or strain components (circumferential or circular). In the event of isotropic deformation, this formula can connect uni-axial strain (or linear elongation) to bi-axial strain (surface expansion).

3. Examples of concepts in actuation

Different actuation theories can be employed to create membrane stretching. We will outline the most popular and promising concepts: pneumatic activation, electromagnetic actuation, piezoelectric actuation, and dielectrophoretic. Different actuation types, including electrothermal, optical and motor-driven actuation, are also being investigated in cell stretch. Several literature reviews have assessed various actuation theories.

Pneumatic actuator

Pneumatic actuation is widely utilized in microfluidics as it can be manufactured using known microfabrication techniques that require just one piece of equipment, an external pressure source. Many pneumatically-actuated systems are built around the deformation of thin membranes, usually made of polydimethylsiloxane (PDMS), which is dispersed by the pressure applied. One example is the well-known organ-on-chip design by Huh and colleagues. (2010) The model bases itself on this principle of actuation (illustrated in Figure 1A). The advantage of this technique is that it creates an even strain pattern across the membrane. Shimizu et al. (2011) have presented a different, advanced application of the pressure drop inside microchannels to produce an array of strain intensities for stretching cells in the device.

Piezoelectric activation

Piezoelectric actuators are the possibility of high-precision alternatives to conventional stepper motors and can create a wide variety of computer-controlled variations of high dynamic. Kamotani et al. (2008) constructed cell-stretching chambers in which the flexible PDMS membrane was placed in every micro-chamber and swayed by piezoelectrically activated pins. Cell cultures within these microchambers were exposed to axial stress (Figure 1B). Piezoelectric-based actuation systems require specific architectures to prevent any direct interaction between the actuator and the cells.

Electromagnetic activation

The non-invasive magnetic field’s non-invasive nature is an intriguing idea in microfluidics. Electromagnetic force-driven actuators offer an adjustable and programmable method of applying strain. However, they inherently cause the heating effect, which must be controlled. Kamble et al. (2017) created a stretching system comprising a PDMS membrane with two permanent embedded magnets situated along the axis of action and the north poles facing one another to generate a repulsive force that results in static strain on the membrane. They employed two electromagnets aligned axially to trigger permanently positioned magnets simultaneously to create cyclic strain.

The actuation of dielectrics

Poulin et al. (2016) have demonstrated the application of dielectric-elastomer actuators to facilitate cell uniaxial stretch [1919. The device comprised an elastomer layer with cells on top, sandwiched between two electrodes with stretchable properties (Figure 1D). A force generated by electrostatic forces was created when a voltage was applied between the electrodes. The result was the thickness of the membrane was compressed and an expansion of the membrane’s surface. The actuation process exposes cells to the electric force. Their study discovered no evidence of damage or effect caused by the electric field on the morphology of cells. In a subsequent study (2018), the same team showed how the dielectric actuation mechanism could achieve a tremendous strain rate (870s-1) and used live-cell imaging to investigate the rapid dynamics.

4. Conclusion and Perspectives

In this review, we have discussed various methods of actuation to create in vivo-like tensile stress through in vitro experiments, with a particular emphasis on integrating organ-on-chip technology. A key aspect to consider when selecting an actuation method is its integration of live imaging techniques for capturing dynamic cell-based processes. Biology data analysis typically depends on fluorescent imaging. Since cell responses to mechanical stimuli may occur through highly dynamic processes, live-cell imaging is essential for various mechanobiology research studies.

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Poker Tournaments for Beginners



Tournaments for Beginners

Since the game of Poker has reached new levels, resorts and casino siteleri where it is played together with the media have not left any chance unexplored to reap the advantages. This is evident in the increase in Poker tournaments.

In the past ten years, there have been numerous Poker tournaments being held on the local level as well as at the national level. The most frequently played poker games in these tournaments include Seven Card Stud, Seven Card High-Low, Omaha Hold’Em, Texas Hold’Em, and community poker, among others.

Poker tournaments are of various types. For instance, shootout tournaments, where players and the tables aren’t eliminated, continue until one player emerges as the winner. In contrast, there are elimination tournaments, where the game starts with each player having the same amount of chips. The game continues until one player can take all chips. The tables are then removed, and only one table is left at the end. Everyone who plays the game to the end table receives a reward to remember. The tournaments are not re-buyable. However, matches with a “Re-buy” option offer the possibility to purchase chips after they’ve been sold. The chips can be bought by paying additional cash. The game will continue for a long time, and there are no chances of being separated.

Additionally, satellite tournaments exist in some areas of the United States, like Las Vegas. These tournaments are played by an entire group of players who are gathered, and each participant puts in several winnings. The lucky winner receives an impressive amount (even over 1 million dollars) to put into various other crucial, costly tournaments.

The prize money for the tournaments of Poker is derived from entry fees. The fees are often called the “buy-in” fees. The money may come into the account of an outside agency or source. However, this money is used for the purchase of invitations. The investment will provide you with the exact number of chips you begin playing with. These chips are your “play money.” The play money can be bought only during-buy tournaments.

The bets on these tournaments are one of three types:

* Structured Betting – bets may only be placed on a certain amount

Semi-structured betting: the chance could fluctuate to a certain extent but not exceed the amount.

Non-structured betting – there isn’t a limit on the amount of money bet. It is the choice of the gambler to bet however much they want.

There are two main ways to decide who is the winner Fixed Winnings and Proportional Winnings. These are the ones where the tournament’s organizer, before the event, decides on the winner. In the second, the winner is determined in proportion. The money is divided between players who remain at the end of the game in proportion to the amount the players have earned during play.

The increasing popularity of this game and the growing number of tournaments has attracted players from across the globe. Because of the intriguing and mouthwatering quantity of money, one can win winning matches, ladies and celebrities would also like to test their luck. So Do you wish to join this Poker world?

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Benefits of installing Penrith Solar Panels for your home:




Are you not able to freely use electricity the way you used to do before, owing to the high electricity costs and inconstant power supply? But, are you aware of the fact that if the power of the sun is properly channelized, it can power up heavy appliances like TVs, ACs, refrigerators, computers, heaters, and other devices without any intervention. At the same time, when you install Penrith Solar Panels, you can cut down on monthly electricity costs. Investing in Green Solar Energy is the future. Besides helping you to minimize your electricity costs, it also reduces your reliance on a centralized power supply and also reduces your carbon fingerprint. Have a look at some of the benefits of embracing solar power for homes.

(1) Save lots of money:  Once you install Penrith Solar Panels in your home, you will install a big dip in your electricity bills. Having solar panels in your home will definitely save on your monthly electricity costs. According to studies, you can save up to 95% of your monthly electricity bills by installing rooftop panels. By making use of the Sun’s energy, the solar panels directly allow you to generate electricity. Therefore, when you switch to solar electricity, your dependency on grid-based electricity is greatly reduced. Once electricity costs get reduced, this, in turn, significantly increases your savings. Year-round service, savings, and efficiency all are ensured by a solar power system.

(2) Escalate the value of your property: Installing Penrith Solar Panels increases your property value by at least 3-4%. Investing in Green Solar Energyautomatically drives up property values offering real estate agents a captivating selling point for real estate agents. When you sell your home, you not only regain the initial cost of the solar system, but also you receive a premium that increases the return on your investment.

(3) Liberty from Centralized Grids: Your dependency on centralized government or private grids significantly decreases once you decide to take benefit of the Green Solar Energy. In weather of inconsistent supply and ever-increasing demand,the safest and the most sustainable bet, in the long run, is to go independent. Installing Penrith Solar Panels provides a safe future investment. You can enjoy additional independence by adding a battery backup to your solar power system. In this way, you can not only generate your own power but also store it for future use, especially if there is a failure of the main grid for some reason or the other.

(4) Contributing to a better environment: Though convenient, fossil fuel-generated electricity is disastrous for the environment. Once you invest in Green Solar Energy, you are actually investing in a renewable and green energy source, which is advantageous for the environment as well. Solar power produces no air pollution, no water pollution, and no greenhouse gas effects and thus, is completely clean. When electricity is produced by solar panels, there is no release of any harmful emissions and is also carbon-free. The need for finite resources is also reduced. Enjoy your clean, renewable power every day continuously and that is too guilt-free.

(5) It is not that expensive: The initial cost of installing Penrith Solar Panels can be high, but there are subsidies and government schemes that offer rebates to aid with the initial costs. And, remember, that this is a one-time investment. They are extremely durable and over their productive lifetime, which spans 25 years or more, they require very little or almost zero maintenance. They are also very easy to maintain. You only need to occasionally dust the solar panels which will remove dirt, leaves or any other fragments that might have accumulated over time. You can also call for a professional, once in a while to clean these panels.

(5) Don’t require additional space for installation: One of the biggest advantages of installing Penrith Solar Panels is that you can install them on any type of roof. So, there is no need to invest in purchasing additional land or empty land to set up rooftop solar panels. Moreover, when you install these panels, they also protect the roof of the building.

(6) Solar Power has multiple applications: Besides the generation of electricity, several other purposes can also be met by solar power. You can solar power to heat water and supply hot air or water to a building. Electricity generators can also be run by it.

The Bottom Line:

The most popular type of alternate electricity that can be effortlessly installed in your home is solar power. Not only is Green Solar Energy a sustainable and reliable power resource, but, if properly channelized, can it run each and every device in your home. Presently, for all your electricity concerns, the most sustainable solution is to opt for Penrith Solar Panels, which has several environmental and economic benefits also. Invest in solar rooftop systems for better service, more savings, and an improved lifestyle.

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Pros of Outsourcing an AC Repair Company in Bloomfield!




With the rising advancements in technology, there is an incredible spike in the usage of electrical products worldwide. Did you know that more than half of all homes in the modern US have an Air Conditioning (AC) machine installed? Constant usage of such a machine can likely place you in the worst situations. For instance, your AC may stop working on the hottest day of the year or stop functioning efficiently due to irregular maintenance.

Needless to say, every Air Conditioning machine requires repair at some time or the other. To keep your AC system in its best condition, you should either have the professional skills to repair the machine or outsource an air conditioning repair company. Although fixing your AC system on your own can offer some benefits, hiring a service provider is much more beneficial. A regular inspection by professional experts of air conditioning repair service in Bloomfield is the best way to keep up the performance efficiency of your AC system.

Still in doubt, whether to hire AC repair professionals or not? Here are the powerful advantages of outsourcing an AC repair company in Bloomfield.


Be it bathroom plumbing repair, gas pipe installation, AC repair, or water main installers in Southfield, Bloomfield, or any other part of the USA, professional repair experts are always well-versed in the entire process. They have the knowledge, training, and expertise to repair the systems quickly and efficiently. It goes without saying that hiring a pro is better than repairing the system on your own. That’s more so because

professionals can even repair the damaged parts or units of your AC system that you are completely unaware of. Moreover, they can efficiently find out the hidden issues with your air conditioning system that is costing you cool air.


Perhaps you must be extremely good at repairing and inspecting your AC machine yet you may find yourself unconfident while executing the process. However, hiring professionals for professional AC repair services can help you achieve reliable results. Please note that professionals are correcting air conditioning-related issues day in and day out. And thus, they know how to handle a wide of issues related to AC systems. Furthermore, their trained skills in AC repairing ensure to deliver excellent results. This is one of the most crucial reasons for outsourcing professional repair experts as an ineffective repairing service can prove to be both – expensive and time-consuming.

Accurate Pricing

It has been often observed that contractors quote inappropriate estimates of the overall AC repairing expenses. This makes you end up spending much more costs than you had initially expected. To combat this pricing issue, it is better to hire a professional air conditioning repair service in Bloomfield. That’s more so because professionals possess years-long expertise and experience, required to produce accurate estimates. However, it’s equally important to be cautious while partnering with an AC repair company. You should thoroughly check the repair company’s testimonials of previous customers. This will enable you to make sure whether the repair company you have chosen is a trusted and reliable company or not.


Completing AC repair tasks on your own might cause potential problems for you and your air conditioning machine. It is more relevant if you are not professionally skilled enough in repairing AC systems. Given the fact that professional air conditioning repair service providers are trained and skilled, it’s the best decision to hand over repair tasks to them. Additionally, hiring professional AC repair services allows you to comply with the safety codes involved in repairing AC systems. Hiring professionals allows you to save yourself and your family members from potential risks. Because professionals are skilled and know the right ways to treat a problem related to AC repair.

Saves Time

A professional air conditioning service provider can complete the repairing task much faster than you. Due to their immense expertise and experience, they have the capability to handle repair issues in the most efficient ways. Moreover, while repairing your AC system can distract you for a wide variety of household reasons, professionals are most likely not to get distracted by other home systems or household assignments. An efficiently functional air conditioning system is very important for a household’s comfort. And thus, you should essentially consider outsourcing a reliable air conditioning repair service in Bloomfield.


Hope this blog helped you understand the importance of hiring a trusted AC repair service provider. The above-mentioned points are just a few of the several benefits of hiring a reliable air conditioning repair service in Bloomfield. To sum it up, professional air conditioning repair experts are trained, skilled, knowledgeable, and experienced in dealing with issues related to AC systems. That said, when it comes to bathroom plumbing repair, gas pipe installation, AC repair, or water main installers in Southfield, Bloomfield, or any other part of the USA, hiring a professional service is always a reliable source of investment!

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