Mass production of cell-sized robots

Researchers have discovered a method to mass-produce extremely tiny robots, the size of a cell, a method that could be used for industrial or biomedical monitoring

Tiny robots, the size of which does not exceed the size of a human cell, could be mass-produced using a new method developed by researchers at the Massachusetts Institute of Technology, MIT. These microscopic devices, which the research team members call "syncells" (synthetic cells), will be able, at the end of the development process, to monitor the conditions that exist inside a petroleum or oil pipeline, or even search for and locate diseases while moving in the bloodstream. The key to making such tiny devices as part of mass production lies in a method developed by the researchers to control the natural crushing process of fragile materials with a thickness of one atom so that pockets of predictable size and shape will form inside them. Inside these pockets the researchers were able to embed electronic circuits and other materials capable of collecting, recording and emitting information. The innovative process, known as "autoperforation", is described in an article published a long time ago in the prestigious scientific journal Nature Materials, by Professor Michael Strano.

The system uses a two-dimensional configuration of a network of carbon atoms called graphene, a material that makes up the outer structure of the tiny synthetic cells. A single layer of the material is placed on a surface, then tiny dots of polymer material, which contain the electronic components of the devices, are embedded into it by an advanced version of an injection printer-type device. In the next step, another layer of graphene is placed on top of the first surface that already contains the electronic components.
People imagine the material graphene, an extremely thin and very strong material, as a flexible surface, but it is actually quite a fragile material, explains the lead researcher. However, instead of treating this fragility as a problem, the research team found a way to take advantage of this characteristic. "We discovered that this fragility can be exploited," explains the lead researcher. The new method controls the crushing process so that instead of getting random fragments of the material, similar to shards of broken glass, pieces with defined sizes and shapes are obtained.

"We discovered that we can infuse a hybrid field that will cause the crushing to be directed, and then this mechanism can be used to control the quality of the material produced," explains the researcher.

When the top layer of graphene is placed on top of the array of polymer dots, which form the shapes of rounded pillars, the places where the graphene cover was over the rounded edges of the pillars create a path of high transition in the material. "Imagine a tablecloth that is slowly placed on the surface of a round table. One can easily imagine the formation of the rounded transition towards the edges of the table, and this is very similar to what happens when a flat sheet of graphene is placed on top of these printed polymer pillars", explains one of the researchers. As a result, the fragments are concentrated exactly along this outline. In the next step, an amazing thing happens: the graphene breaks completely, but the breaks are oriented along the perimeter of the columns." The result is a round piece of graphene that looks like it was created by a microscopic punch. Since there are two layers of graphene, above and below the polymer pillars, the two discs that are formed stick to each other at their ends, similar to a tiny pita, with the polymer trapped inside. "And the advantage here is that everything is created in a single step, this is in contrast to many other complex steps that are carried out in a clean room as part of other processes designed to create microscopic robotic devices", notes the researcher. The researchers showed that other two-dimensional materials, such as molybdenum disulfide or hexagonal boron nitride, also work in the same way.

These tiny objects, whose size range extends from the size of a human red cell, with a length of ten micrometers, to ten times that size, "begin to look and behave just like a living biological cell. In fact, if we put them under the microscope, we can convince most people that it really is a structure of a cell," says the researcher.

This research is based on previous research by Strano's group in which the team of researchers was able to develop synthetic cells that are able to collect information about the chemistry or other properties of their environment, using detectors on their surface, and which are able to store the information so that it can be retrieved later ; For example - injecting a collection of such particles at one end of a pipeline and collecting them at the other end of the line in order to collect data regarding the conditions existing inside the pipeline.
Besides the possible uses of these synthetic cells in the framework of industrial or biomedical monitoring, the method for preparing these devices is itself a new invention with multiple capabilities, according to the researchers. "This general procedure for using oriented fractions as a manufacturing method could be extended to many other applications." It will actually be possible to use this method for any type of two-dimensional material, when researchers will have the opportunity to customize these monoatomic surfaces to any shape, structure and size they require in other fields."

The researcher explains that the new method: "is one of the only methods available today for the independent production of integrated micro electronic components on a commercial scale" that may function as independent devices. Depending on the type of electronic components inside, the devices could provide capabilities of movement, detection of chemical substances or other properties, and even memory storage.

To demonstrate the applications of the innovative method, the research team etched the letters MIT onto a synthetic cell memory array, which stores the information as variable levels of electrical conductivity. In the next step, this information can be "read" with the help of an electrical test device, a fact that proves that the material can function as a type of electronic memory where data can be written, read and deleted. The device will be able to save the data without consuming electricity, a fact that will allow collecting information at any time later. The researchers demonstrated that the particles are stable for a period of many months, even if they float in water, a solvent that is normally harmful to electronic components. "I believe that our method provides a completely new tool for the micro- and nano-manufacturing industries," says the researcher.

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An image showing the circles on a graphene sheet separating from each other due to pressure. [Courtesy: Felice Frankel]