Sensors make the Internet of Things (IoT) “go.” Typically, they’re chips or modules, but what if they could be printed? This creates all sorts of possibilities. I talked with Brewer Science’s Will Stone to find out more.
Will Stone, Director of Printed Electronics Integrations and Operations, Brewer Science Inc.
Why is there an increasing need for printed sensor arrays and systems?
Printed sensors and arrays offer capabilities that are unavailable in traditional silicon sensor systems. Printed devices tend to allow for more flexible form factors due to their low profiles and bendable substrates. Material cost can also be reduced by combining the sensors with the measurement system on a single substrate.
What are the main differences between printed and traditionally manufactured sensors, in terms of both technology and business model?
The outcome of the measured characteristic will be the same with both technologies. If the goal is to measure temperature, both technologies will result in the same temperature value. Where printed sensors have the advantage is their sensing speed and form factor. Due to the advantages of our printed sensing technologies, we can sense at a greater speed than many silicon sensors. In addition, our sensors can fit into narrow spaces or follow contoured shapes where traditional rigid sensors and circuit boards will not fit.
Brewer Science’s InFlect FHE Flex Sensor can be used for VR gloves, medical devices, and industrial 4.0 applications.
What applications or markets offer the most immediate opportunities for printed sensors, and which applications or functions do you see driving future/longer-term adoption?
Custom form factors and flexibility of design are currently driving the market. While flexible printed circuit boards (PCBs) have existed for some time, they are still costly to manufacture compared to flexible hybrid electronics (FHEs). The additive nature of FHEs is also less impactful on the environment as no toxic etching solutions are needed, unlike traditional PCB manufacturing.
Most designers have used traditional sensors but may be unfamiliar with printed ones. What are some of the challenges in developing systems with printed sensors?
Printed sensors will behave similarly to their silicon counterparts. The challenge is in the change of mindset to create an FHE system and incorporate the sensors with the measurement device in a flexible/bendable form factor. Engineers and developers have just dealt with the design challenges of rigid PCBs in the past. Now with FHEs, they have a greater freedom to let their imagination create product designs that were cost-prohibitive in the recent past.
How does Brewer Science help designers overcome those design challenges?
We provide design assistance to aid our customers through the FHE design process. This can include review of CAD and circuit designs, suggestions on sensor selection, firmware and algorithm strategies, and manufacturing of the finished design. We can participate in the design cycle and production as much or as little as our customers request.
Brewer Science can design and print custom interconnect cables, such as this one, which create a flexible and durable connection between different components.
How are printed sensor technologies implemented?
Starting at the materials level, at least three different types of inks and materials are required to design a printed sensor. First, a conductive ink acts as an interconnect between the sensor and the device with which it’s communicating. Next, an ink that contains the desired sensing characteristics is used to create the sensor itself. Finally, a material is needed that can act as an encapsulant for the sensor materials and conductive inks.
Design is as critical as the material sets and substrates for creating a printed sensor due to different properties that not only affect the material composition, but also will need to withstand different environmental conditions. After the design, materials, and substrate are determined, the next step is to choose the printing method. Many different quality methods right now can be used for printing sensors, including screen printing, inkjet, gravure, and flexo printing. Once the printing method is selected, final optimizations are implemented and the sensor is produced.
What are advantages and challenges of printed sensors?
The advantages over traditional silicon sensors include speed, precision, durability, and flexibility/conformability to various form factors. The current challenges with printed sensors are their lack of standardization, maturity, and market acceptance.
Where are printed sensors being implemented?
The typical implementations of printed sensors are in locations where conventional sensors will not fit. These locations include narrow passageways, around curved surfaces, and in unique high-speed applications. Printed sensors can solve these issues with their slim design profile and bendable form factor, as well as their extremely fast responses to stimuli. We see applications from warehouse and manufacturing monitoring to in-field agriculture to automotive applications. Basically, anywhere a traditional rigid sensor will not meet the design requirements.
This Brewer Science temperature-sensor array is printed on a Kapton that’s used for multi-point sensing.
What’s your vision for the future of printed electronics?
We will see printed electronics in designs never thought possible. Electronics in clothing and consumer products will be as common as today’s smartphone. Printed electronics will continue to displace traditional PCB designs where non-traditional form factors and bendability are needed.
A graduate of Missouri State University, Will Stone has spent nearly 20 years in developing automation and monitoring systems, ranging from intrusion and fire protection to industrial engine systems monitoring. In his current role, Will runs Brewer Science’s printed electronics development program. It focuses on unique solutions to integrate flexible sensor technologies that monitor water and air quality for industrial IoT applications.