Cilia can also be used as chips! A work by a Chinese doctoral student from Cornell appears on the cover of Nature

What is the most important step in making chips?

In addition to using more advanced manufacturing processes to bring greater transistor density and obtain greater computing power, the transmission and control of internal signals within the chip It is also an essential part.

# "Cilia Chip", do you want to know about it?

#Of course, let’s first look at what cilia do.

Cilia can be said to be the most diligent messengers and messengers in organisms. To put it more directly, they are the most flexible "porters" of liquids.

These slender hairs move fluids in the body, including cerebrospinal fluid in the brain, and clear phlegm and dirt from the lungs through rhythmic beating. materials to keep other human organs and tissues clean.

#For many years, people have hoped to absorb, or "borrow", the magical abilities of cilia in the fields of computing and control.

#But on a micro level. It is very difficult to replicate the "miracle" in this organism. In the past few years, research on optical, magnetic and electric drives has made a lot of progress, but a "cilia-driven" platform with engineering application value is still difficult to realize.

#Now, this difficulty has been solved by a group of researchers at Cornell University.

#They designed a miniature artificial ciliary system using platinum-based components that can use cilia to control the movement of liquids at a microscopic scale. In the future, it may be possible to implement low-cost, portable diagnostic devices that can be used to test blood samples, manipulate cell activity, or assist in micromachining processes.

Currently, a paper published on this research has been published in the latest Nature. The first paper is by Chinese doctoral student Wang Wei (pictured above), 2. As a Chinese postdoctoral fellow, Liu Qingkun, his papers have been cited more than 2,300 times and his H-index is 24.

Wang Wei said that there are already many methods to create artificial cilia driven by light, magnetism or electrostatic force, but we are the first Team uses new nanoactuator to realize artificial cilia that can be individually controlled.

Paper link: https://www.nature.com/articles/s41586-022-04645-w.pdf

In this Nature paper, researchers constructed an active metasurface that drives electronically driven artificial cilia and can generate arbitrary flow patterns in liquids near the surface.

The researchers first constructed voltage-driven cilia, which move unidirectionally at a speed of tens of micrometers per second under a driving voltage of 1 volt to drive Surface flow. Ciliary unit cells can locally generate a series of element flows and form different geometric shapes.

Artificial cilia based on surface electrochemical actuators

Through combination With these unit cells, the researchers created an active ciliated metasurface that can generate any desired flow pattern and flexibly switch between these patterns.

#These results were finally confirmed through experiments and theoretical calculations.

The researchers say these results open up a new path for future fine-scale microfluidic manipulation, with applications ranging from microfluidic pumping to microrobot movement. .

Microscopic view of artificial cilia

Specifically, a typical "cilia chip" contains 16 square units, each unit has an array of 8 cilia, each array has 8 cilia, and each cilium is about 50 microns long, forming a "carpet" composed of about 1,000 artificial cilia.

Apply an oscillating voltage to each cilium, and periodic oxidation and reduction will occur on its surface, causing the cilium to bend back and forth at dozens of times per second. Pumps fluids at micron speeds.

Different cilia arrays can be activated independently, thus creating endless flow patterns and routes, almost as flexible as cilia in living organisms.

The research was led by Itai Cohen, corresponding author of the paper and professor of physics at Cornell University, and was built on a platinum-based electric actuator. , as a core component of the ciliary apparatus.

#Cohen’s team previously built a similar system that allowed microrobots to walk. In fact, the mechanical principles of making microrobots "bend their legs" are very similar to this research, but the specific functions and applications of the ciliary system are different and quite flexible.

Multiple flow routes generated by ciliary units

Cohen said, "Once you can handle these cilia individually, you can precisely manipulate and control these fluids in any way you want. You can create multiple independent trajectories, achieve circular flow, or split into two paths and then flow between them. All in one. You can even design routes in three dimensions. In short, everything is possible using existing platforms. Creating cilia that work in water, are electrically processable, and can be integrated with interesting electronic devices has been very difficult. Now that this problem is solved, we can hope to develop the next generation of microfluidic devices. "He said.

In addition, the research team also developed a ciliary device equipped with a CMOS clock circuit, which is actually an "electronic brain" that allows the cilia to be protected from traditional computers. Operating without system constraints also opens the door to the development of a range of low-cost diagnostic tests that can be performed in the field.

#Cohen said that it is conceivable that in the future, people will hold this small device that is 1 cm square and just put a drop of blood on it. Perform all tests. There is no need for a pump or any other equipment, just put it in the sun and it will work, and the cost may only be around $1 to $10.

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