With sensors’ ubiquity and demand exploding, manufacturers are turning to flexible and printed electronics, which allow them to implement sensors in novel ways. Eliminating the complexity of traditional circuitry opens up a new world of possibilities. But what is at the core of these new developments? As it turns out, it is some of the same materials expertise that enabled advancements in traditional semiconductors.
The market for printed electronic systems is expected to double from its 2017 level, reaching $60 billion by 2025 (Figure 1). This is due, in part, to the emergence of a ubiquitous internet of things (IoT) – which has, in turn, been enabled by key advancements in materials science, including:
- Using semiconductors for flexible hybrid electronics
- New methods of composite ink formulations
- New signal enhancement layers and filters
- Printing process improvements
- Enabling aqueous electrodes and wearables, and other new products
Fig. 1: The printed electronics market will reach $60 billion by 2025. While OLED displays will retain their dominance, sensors will represent a growing share of the market.
Printed electronics manufacturing involves printing electrically and/or chemically functional inks and other materials onto a substrate in layers to create electronic devices. The makeup and availability of these inks and materials varies widely (Figure 2). Leveraging the properties of unique materials allows researchers and device manufacturers to fine-tune their devices for specific needs, such as versatility, connectivity, ultrafast response time or ease of integration.
Fig. 2: The content and availability of materials used to make printed sensors impact the choices made during sensor design.
Why Sensors?
A printed electronic system cannot function without the underlying materials (Figure 3). A key requirement for building a successful IoT or industrial IoT application is the ability to produce sensors in high volumes at a reasonable cost. This allows for a much wider array of sensor types as part of an interconnected network of devices. While temperature and humidity sensors can also be produced in rigid form at high volume and low cost, printed electronics present an additional unique advantage: low entry cost—there is no need to invest billions of dollars in building a fab.
Fig. 3: This graphic illustrates how many different types of materials can be found “under the hood” of a typical flexible hybrid electronic (FHE) sensor.
Another reason for this market’s attractiveness, from a materials perspective, is the flexibility—both physical and conceptual—of printed electronics. Applications can be pursued with flexible/printed electronics that are literally impossible using traditional rigid devices. Kinesiology presents a substantial opportunity, as new wearable applications will enable the earliest reach of sensors and printed or flexible hybrid electronics to a broader audience.
The reality is that the technology, while promising, is still young. Pursuing engagements in developing future sensing solutions involves finding companies that are willing to take a risk; i.e., startups that are doing what no one has ever done before.
This includes companies in the artificial intelligence (AI) arena. The IoT cannot reach its full potential without AI because machine learning is essential to finding patterns, correlations and anomalies in the massive amounts of data generated from connected sensors and other devices. So, what role do materials play here?
Materials to AI – not such a stretch
It’s natural to think about AI in terms of an algorithm—a string of code that’s working its magic to extrapolate data—but AI is only as useful as the information it’s receiving; i.e., the code can only function based on the information it’s receiving. The components in the device feeding the information are the driver, and the design of these sensors—starting at the foundational material level—is critical to how they function. Using materials specifically designed for sensor development is therefore essential. To put it more bluntly, “garbage in, garbage out.” Users need information that is useful and not merely voluminous, particularly as sensing becomes increasingly ubiquitous.
To recognize the need for quality materials throughout the development of a product, it is essential to understand the importance of the “ingredients” that go into the solution. This is where experience in developing materials for semiconductor applications comes into play (e.g., photolithography, wafer-level packaging or adhesives for chip stacking). Traditionally, the tendency was not to take into account the importance of the materials being used. It took a long time for players in these markets to embrace the importance of materials for device optimization and excellence, but that cycle should be shorter with printed electronics.
Another point to consider regarding how materials are applied in a sensor is design functionalization. A gas sensor is an example. Technology based on a carbon nanotube (CNT) type of approach creates the foundation of the active-layer material. What is added to that platform can impact the exact gases that need to be sensed. Materials that make it more sensitive to certain types of gas must be added, as well as filters for what should not be detected.
Environmental sensors are another area where it is easy to see the difference that materials selection can make. Sensors that monitor and detect changes in water quality, for example, can be optimized to only detect content that is necessary to the end user as a vital piece of information. Contaminants that are important to filter out of drinking water may not need to be detected in lake water. Sensor design—starting with materials—is critical to filter out such “noise” so that sensors operating in specific types of environments can yield meaningful data.
Summary and Conclusion
Materials design is a vital component of printed sensor systems. Clearly, then, materials expertise matters when it comes to enabling the printed electronics used in sensors, particularly connected IoT-enabled sensors.
Brewer Science is one company that is pursuing this path by leveraging its core technology and expertise in material science. The evolution has been an organic one, as the company recognized that this proficiency can be used not just to make materials for inks, but to create an actual functional device or component for enabling printed electronic sensors. The first efforts to develop sensors based on a CNT platform led to ascending through the value chain toward developing more complex systems that can meaningfully impact this space.
This type of materials expertise allows better decisions to be made when designing sensors for specific applications. In the case of the burgeoning AI market, it is important to design sensors with the best materials for the fastest and most accurate reactions, which are essential to achieving fast processing in AI applications.
Brewer Science Inc. was an exhibitor at Sensors Expo 2018 in San Jose, CA. Brewer Science is a global technology leader in developing and manufacturing innovative materials, and processes for the fabrication of semiconductors and microelectronic devices. With its headquarters in Rolla, Missouri, Brewer Science supports customers throughout the world with a service and distribution network in North America, Europe, and Asia. Learn more at http://www.brewerscience.com.