"Tiny" Sensors, Unlocking Trillion-Dollar Markets

 

Curiosity is one of the innate traits of humanity, driving us to understand and explore the unknown world. As times evolve, the information perceivable by human senses can no longer keep pace with our relentless quest to uncover the mysteries of the world. The advancement of technology has granted us the possibility to enhance and expand our sensory experiences.

Sensors are the wellspring of data collection, omnipresent in our lives.

The situational awareness required at the forefront of intelligence essentially begins with sensors. Whether it's intelligent manufacturing, smart cities, telemedicine, or intelligent devices and big data analysis, every vast intelligent system starts from the tip of a sensor.

Recently, a dialogue was held between the semiconductor industry and Professor Li Xinxin from the Shanghai Institute of Microsystems and Information Technology, Chinese Academy of Sciences, and the State Key Laboratory of Transducer Technology. The discussion ranged from the driving forces behind sensors to future application scenarios. During the exchange, Li Xinxin also analyzed what he believes is the greatest advantage for China in developing sensors.

"The value of a 'one-yuan' sensor can drive the value of 'hundreds of thousands' of yuan in application systems."

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All things in the world ultimately need to be converted into electronic signals to collect electronic data.

There is a vast array of sensor types, and there used to be a saying, "Many varieties, small batches." Sensors span across physics, chemistry, biology, and more, with researchers of different types of sensors often hailing from different academic disciplines. For instance, those studying biosensors may not share the same academic background as those studying physical sensors, yet the fundamental function of sensors remains the same.

The global sensor market is mature, requiring the production of hundreds of billions of sensors annually.

According to data from the German Statista data analysis company, the global sensor market size in 2022 was $251.29 billion (approximately 1.79 trillion RMB). Among this, the Chinese sensor market size was 309.69 billion RMB, with a compound annual growth rate of 12.26% from 2019 to 2022.

Li Xinxin said, "Although the value of sensors may not be high, they possess a driving force, that is, the Driving force. For example, a sensor might be very cheap, costing only one yuan, but the signal processing components that accompany it could be worth 10 yuan. However, one should not devalue the sensor because without its sensing function, the subsequent 10 yuan would be useless; it plays a leading and driving role."

In the industrial environment where digital transformation is accelerating, sensors, as a key link in data perception, are moving towards intelligence. Li Xinxin stated that there are three implications behind the intelligence of sensors. One implication is the sensing effect itself, such as bionic intelligence, which mimics the sensing effects of living organisms, like the compound eyes of a fly. Another implication is brain-like intelligence, which imitates the brainstem, cerebellum, and cerebrum of humans. The third implication is the intelligence demonstrated by sensors in signal processing. Due to environmental interference, the signals output by sensors may not be clear, and at this point, intelligent algorithms such as subsequent circuit calculations and convolutional integration can be used to further purify the signals and improve the signal-to-noise ratio.

Li Xinxin said in an interview, "Sensors involve many disciplines, so many people are interested in them. Many of those interested are 'users of sensors,' but we currently lack attention to 'makers of sensors,' which is the source technology."

"The cheaper the sensor, the harder it is to make."

When discussing the difficulties of MEMS sensors, Li Xinxin said, "The most challenging sensors in the world to make are those that are in the highest demand, require the lowest cost, and do not have high-performance requirements." Taking China as an example, aerospace sensors have achieved self-sufficiency. However, how many sensors in Apple's smartphones are made in China? Sensors need to be cost-effective, and there is a saying: "Cheap is high technology."

Sensors used in the aerospace field may have a success rate of one good one out of ten, and the rest can be discarded without issue. For sensors required by smartphones, if a single specification is not up to standard, it will affect the overall performance of the phone; the defect rate of sensors used in automobiles must be controlled to less than one in a million, otherwise, a failure could have catastrophic consequences.

Therefore, while the application of high-end equipment is strict, it is relatively less sensitive to price, and the high value of the system itself makes an increase in cost of a few yuan not a problem. In fields that are widely used globally and face fierce competition, such as the mobile phone industry, as competition intensifies significantly, cost control becomes particularly strict. Any slight increase in cost can affect the competitiveness of the product in the market. Li Xinxin said, "Technology ultimately has to serve applications while also being realized within a fixed price, which requires strategic trade-offs."

In addition to cost-effectiveness, the manufacturing, testing, and integration of multiple sensors all face different challenges.

In terms of manufacturing, there are still many differences between sensors and integrated circuits. Although MEMS manufacturing technology is derived from semiconductor experience technologies such as photolithography and etching, integrated circuits are often manufactured as flat objects, while MEMS sensors, such as gyros, accelerometers, and pressure sensors, require double-sided processing to form three-dimensional structures. Photolithography masks are two-dimensional planar graphics that are processed into three-dimensional microstructures. Li Xinxin said, "The transition from two-dimensional to 2.5-dimensional or three-dimensional is inherently complex, and this transformation is where the technical difficulty lies."

The complexity of the manufacturing process will undoubtedly increase when many sensors need to be integrated. Different sensors have different requirements for the size and thickness of the structure, and if made together, satisfying one sensor may not achieve the optimal design for another sensor. "People always want to integrate integrated circuits and various sensors on a single chip; the ideal is good, but doing so may result in a low yield, high manufacturing costs, and not guaranteeing that the performance of each sensor is designed according to the best size."

When designing sensor structures, if the qualification rate of a single product is 99%, but if 10 are concentrated together, a simple calculation will show that the yield rate does not reach 99%. If the quantity is even greater, it may not even reach 50%. This makes production meaningless and effective mass production unattainable.

Regardless of the field in which sensors are applied, there is a common demand for reliability. The reliability of a sensor depends on testing. Li Xinxin said, "I have always believed that the testing of sensors is the most difficult, especially the automated testing of large-batch products."

When testing ICs, inputs and outputs are all electrical signals; a pulse sequence is given, and after passing through the logic circuit, delays are measured, etc. But sensors are different; for example, a gyroscope has an angular velocity input and an electrical signal output; pressure sensors require connection to pipes; gas sensors need to input a specific concentration of gas. Testing sensors is difficult, and the difficulty lies in simulating real sensing environment inputs.

Li Xinxin said that a large part of sensors is not electronic equipment, and scene applications must also be considered. In this regard, it is not enough to emphasize production capacity and manufacturing. In terms of testing, especially large-scale multi-type testing, it is difficult to complete within a single factory and must be distributed to multiple factories, and the output of each factory is relatively small, making it difficult to make a profit. The technology that can very flexibly and quickly automate testing for a variety of scenes and different quantities is very challenging.

The Greatest Advantage of China's Development of Sensors

When discussing which fields will promote the growth of sensor technology, Li Xinxin listed the relevant fields in detail like counting beads on an abacus.

The first is the automotive market. The electrification of vehicles means that more and more sensors are needed. Even if it is not an electric vehicle, the cost of electronic components in traditional fuel vehicles has already surpassed that of the engine. In the past, people generally believed that the core of a car was the engine and fuel system, but now, in the composition of car value, the proportion of the fuel system is less than that of the electronic components. To achieve effective control, the first task is to use sensors to obtain sensing data.

The second is the market for consumer electronic products such as mobile phones. The mobile communication equipment and consumer electronics market is quite large, and thanks to the miniaturization, low power consumption, low energy consumption, and large-scale production advantages of micro-electromechanical systems (MEMS) sensors, these sensors can achieve low cost and miniaturization and are widely integrated into smartphones.

The third is the medical market. To prevent cross-infection, many medical products are designed for single use. For example, during the installation of stents, disposable sensors are needed to measure arteries; during brain surgery, disposable intracranial pressure sensors are also needed. The above situations all constitute the main driving force for the development of sensor technology.

The fourth is the Internet of Things, smart buildings, smart cities, and smart earth, etc. These scenarios cannot achieve intelligence without the application of sensors. The premise of achieving intelligence is to ensure that everything is controllable. For example, the CMOS chips used in photo-sensing cameras are also the core components of smartphone cameras. In the construction of smart buildings, a building may have tens of thousands of air outlets, each equipped with sensors to adjust the air volume in real-time, thereby achieving energy saving, improving comfort, and work efficiency.

Li Xinxin said, "As the world moves forward, it is increasingly difficult to find a single direction as the driving force. All walks of life, including the electronics field, including semiconductors and sensors, have penetrated every cell of society. In the future, everyone may have many sensors, and multiple sensors are needed to collect data to make judgments, and none of them can be dispensed with."

When talking about the development of sensors in China, what advantages does it have? Li Xinxin said that China's biggest advantage lies in the market.

He recalled that in the past, he had worked in Singapore, where scholars and researchers also made many achievements, but it was difficult to find application scenarios. High-end products needed to be imported from the United States, and low-end products from other countries. Although Singapore is in the industrial chain, it cannot see the source of scientific research or the end of the application, so it is relatively passive.

China has a huge market, and China's economic system, including aerospace and national defense, is relatively independent and complete. We often talk about the localization of aircraft and even pay attention to whether the engine can be localized to avoid a passive situation. China is striving to build a stronger industrial system. In this case, sensors are very useful, and many sensors need to be localized.

China is a big country with comprehensive disciplines. Sensors involve many disciplines such as light, force, heat, electromagnetic, biology, and gas. Some smaller countries, even advanced countries, may not be able to take care of all fields and cannot fully deploy, only focusing on one or two fields that are most suitable for their industry. China is important in all aspects, the market is large, and the demand is also strong. This provides a good opportunity for scientific researchers, especially those in the field of sensor research.

Li Xinxin sighed, "China has a relatively rich and complete system, allowing scientific researchers and practitioners to have a target and a place to use their skills. As long as it is done well, a suitable application scenario can be found."