I, a nanometer material researcher, how did I spark with track cycling?

2024-08-18

On the track cycling field, to break through the limit of 0.0001 seconds, to make the competition fairer, what have nanoscientists done?

 

On July 21, 2024, Zhang Ting, a specially appointed visiting researcher at the Sports Science Research Institute of the General Administration of Sport and a member of the Institute Affairs Committee of Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, brought a speech titled "The Extreme Breakthrough of 0.001 Seconds" to the popular science China Star Lecture "Scientific Perspective on the Olympics" themed session.

 

 

The following is an excerpt from Zhang Ting's speech:

 

Hello everyone, I am Zhang Ting, from the Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences.

 

My research direction is intelligent micro-nano sensing materials and devices. In simple terms, it is to use nano materials and structures to develop highly sensitive and fast response intelligent sensing devices.So, how does our sensor create a spark with the Olympics?

In modern Olympic competitions, every millisecond and even every microsecond is crucial. This is especially true in track cycling, where the speed of contemporary track bicycles can exceed 20 meters per second, and the difference between top competitors is often just a matter of milliseconds.

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For example, in 2016, at the Rio Olympic Games women's individual sprint final in track cycling, the German athlete won the gold medal with a 0.004-second advantage. Therefore, in the Olympic arena, every breakthrough of a thousandth of a second is extremely important.

We have a slogan: "For a thousandth of a second, exhaust all possibilities." We hope to rely on the power of technology and the integration of disciplines to break through the limit of 0.001 seconds.High-Precision Timing Systems Are Essential

For track cycling competitions, high-precision timing systems are indispensable.

At present, there are two Olympic-recognized timing systems globally, both of which are monopolized by foreign companies. Due to the design of these foreign timing systems for events, they are very expensive, with each set costing over 2 million yuan, requiring multiple people to operate, and their current functions cannot meet the personalized needs of coaches and trainers. At the same time, our national team is still using manual stopwatches or video analysis methods, which are not only inaccurate but also time-consuming and labor-intensive, with slow feedback speed.

How does the working principle of a high-precision timing system work? It installs a pressure detection strip on the track. When the bicycle passes over the detection strip, it generates an electrical signal, which is received and processed by a tracking box to achieve timing. Such systems are not only expensive but also have significant shortcomings.

For example, the pressure detection strip currently used abroad utilizes two layers of curved copper plates to achieve pressure detection on the bicycle through contact and separation. This leads to two crucial problems:One issue is related to the materials because when the bicycle passes over the detection strip at high speed, the two layers of copper plates will collide, generating a strong static electricity, which can affect the system and may lead to inaccurate signal monitoring.

The second key issue lies in the two layers of arc-shaped copper plates, which make the pressure detection strip relatively thick. Just like when driving over a speed bump, there will be a jolt. During the race, when the bicycle passes over this protruding detection strip at high speed, it will also bring a brief impact, causing the bicycle to slow down. This may pose a great safety hazard, increasing the risk of the rider falling or getting injured, and is also very unfavorable for competitive racing.

Therefore, we urgently need to develop a more advanced high-precision timing system with independent intellectual property rights to achieve domestic substitution, which is of great significance for improving the core competitiveness of our country's track cycling.

To achieve this goal, the key is to break through the independent development of the core sensing components of the high-precision timing system, including high-performance pressure detection strips, tracking boxes, start command control consoles, and software systems, etc.How to achieve the goal?

To develop a more advanced pressure detection band, we innovatively utilized nanotechnology to design a carbon nanotube composite material that is highly sensitive to pressure.

Carbon nanotubes are a very unique conductive nanomaterial, with a diameter 10,000 times finer than a hair strand, and a tensile strength 100 times that of steel, which can perfectly solve the problem of the pressure band being too thick.

Next, we need to address the issue of precision.

For this, our team thought of many methods, and in the end, it was the game sticks that brought us a lot of joy in our childhood that inspired us. The scattered game sticks can be connected to each other to form a network. You can imagine that if carbon nanotubes are also connected in this way to form such a network, any disturbance of a single stick can significantly affect the performance of the entire network.The ingenious material composite process allows these conductive carbon nanotube nanomaterials to scatter and interweave into a network. When a bicycle wheel quickly rolls over, within the square inch under the wheel, millions of carbon nanotubes will undergo morphological changes and changes in electrical properties, causing the conductive network to fluctuate rapidly and significantly. In this way, we can accurately record the moment when the bicycle comes into contact with the detection strip.

Making carbon nanotubes into conductive ink

With the above design principle, the next step is to achieve a highly sensitive flexible pressure sensing strip device and mass production through repeated experiments, which is also one of the core challenges. To this end, we need to explore, try and iterate repeatedly over a long period.

First, we disperse these carbon nanotubes in the reagent to make a uniform composite conductive ink. Its advantages are good uniformity, controllable fluidity, and can be printed on many flexible substrate materials through printing or 3D printing methods.Then, we further optimize the printing process, as well as control the physical and chemical properties of the flexible substrate materials, to make the flexible substrate and carbon nanotube composite film have a very strong binding force, thereby increasing the stability of the device. In this way, during bending and use, the sensitive materials will not fall off from the surface of the flexible substrate. As a result, we have obtained this thin, soft new type of flexible pressure sensor.

Its thickness is only 0.3 millimeters, as thin as a piece of paper. Therefore, when the wheel quickly rolls over, it can greatly improve the accuracy of detection without causing the bicycle to slow down, and also greatly improve safety. At present, our flexible pressure detection belt can be made up to 8 meters long and can withstand more than 1 million times of repeated rolling over by a bicycle at a speed of 90 kilometers per hour.

On this basis, we have further solved the problems of batch integrated molding of flexible pressure sensors, and finally achieved the mass production of high-precision flexible pressure detection belts for field cycling tracking and timing through flexible packaging and interface design.

So far, we have completed the first step in the development of a high-precision timing system.Next, we deployed this internationally pioneering flexible pressure detection belt, which is the first of its kind, on the track cycling course in the training venue in Beijing in a distributed layout, with more than seven belts. This is an image of athletes passing through the flexible pressure detection belts one after another—

Duration: 00:05

Control the counting error within a ten-thousandth of a second.

The second step of our research work is to quickly and synchronously transmit and process the signals detected by these flexible pressure detection belts, which is also a challenge.For this purpose, we have joined forces with the team of Professors Zhong Daidi and Huang Zhiyong from Chongqing University to establish a distributed time synchronization network, which keeps the entire counting error within one ten-thousandth of a second.

Additionally, during high-speed cycling in a velodrome, the tires and the floor continuously rub against each other, accumulating a large amount of electrical charge. When this charge comes into contact with the pressure belt, it can cause a strong discharge of tens of thousands of volts, which greatly affects the accuracy of information collection and the safety of the system.

Therefore, we have adopted various methods such as precise discharge, hardware isolation, and software filtering to harmlessly process some strong interference signals that may be generated from the outside, ensuring the accuracy of data collection and the safety of the system.

Precise control of the starter gate opening time

Before the start signal, the track bicycle is controlled by the starter. After the countdown time for the start signal is over, the timing system delays the opening of the starter by 100 milliseconds, and the athlete quickly responds and starts.This involves the third core component of a high-precision timing system: the start command control console.

In this process, the athletes' reaction times are crucial to the competition results. Generally, athletes will undergo repeated training based on the start gate's opening time, thereby forming muscle memory.

At the same time, this also requires us to precisely control the opening time of the gate when designing the starter, and the control precision must also reach one-thousandth of a second. Otherwise, if it is too early, it will cause a "false start," and if it is too late, it will affect the athletes' performance.

The opening of the gate belongs to mechanical motion. To control the precision of mechanical motion within such a short time is very difficult. We have joined forces with the team from Chongqing University, using high-speed cameras combined with high-precision control algorithms, to achieve precise control of the gate opening time, with the error controlled within one ten-thousandth of a second.Integrating the aforementioned research, we have achieved a breakthrough in high-precision timing systems that surpass the 0.001-second threshold through interdisciplinary collaboration with multiple groups.

In the future, we will continue to optimize, such as introducing more sophisticated micro-nano structures, by optimizing mechanical and electrical models to further enhance the pressure sensitivity of the flexible timing belt, striving to improve the timing accuracy to the microsecond level.

In fact, these technologies are not only applicable to track cycling, but also to sports events such as fencing and boxing, where this type of flexible intelligent sensing technology can be utilized.

At the same time, our flexible intelligent sensing technology based on nanotechnology can more deeply coordinate with information collection, transmission, and processing systems to reduce counting errors; through intelligent algorithms, multi-technology integration, and grid layout, to achieve real-time and precise perception of the bicycle's position and speed, ushering track cycling into a comprehensive intelligent era, making sports more scientific.

How can new materials be used to reduce resistance further?In fact, the application of new materials and new technologies in the Olympic field is not limited to this.

We are also exploring the possibility of reducing bicycle resistance by combining bionics design, and have made some progress.

We have joined hands with Professor Yuan Weizheng and Professor He Yang's team from Northwestern Polytechnical University to test and measure the frame, wheels, handlebars, cycling clothes, helmets, and the riding posture of each cyclist in the wind tunnel, to find out the possibility of reducing resistance from these six aspects.

We have drawn on the unique tongue-shaped fractal sand ridge structure of the Kumtag Desert in Xinjiang, China. The undulation of the sand ridge surface can affect the flow of the wind, forming a relatively smooth distribution of resistance. This distribution can maintain a higher flow speed and flow rate of the wind as it passes through the sand ridge, thereby reducing resistance and energy loss.Inspired by biomimetic design, we have, for the first time internationally, designed and manufactured a bionic sand-dune micro-nanostructure drag reduction film. By combining aerodynamic theories, we have designed unique micro-nanostructures specifically for the rotation of bicycle wheels and helmets, achieving a drag reduction rate of 3%.

Simultaneously, we have collaborated with Professor Su Weifeng's team from the Beijing Normal University - Hong Kong Baptist University United International College. By utilizing artificial intelligence methods such as motion estimation intelligent algorithms and computer vision technology, we have efficiently and intelligently analyzed motion images. Combined with ground timing belts, we have formed a multi-dimensional, multi-modal precise spatiotemporal judgment that can eliminate millisecond-level errors in competition.

We hope that through the intersection of multiple disciplines, by integrating nanotechnology, biomimetic technology, and AI technology, among others, we can build the most accurate clock, making the competition fairer and contributing to the Olympic athletes' pursuit of "faster, higher, stronger."

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