Whether you work in aerospace, defense, or the medical field, embedded sensing capabilities are playing a greater role in new devices and technologies. These capabilities allow internet of things (IoT) and autonomous devices to have greater interaction with the analog world in which we live. While still in the proof of concept phase, the ability to fabricate embedded sensors with 3D printing provides capabilities that go far beyond those provided by commercial off-the-shelf (COTS) sensors. This requires unique fabrication techniques that are best achieved with additive manufacturing.
Temperature and humidity sensor board from Phytec
What Is an Embedded Sensor?
In the simplest sense, an embedded sensor is a small system that contains sensing elements, as well as some data and signal processing capabilities that is embedded within a circuit board, an electromechanical part or larger system. IoT devices with embedded sensors can have these capabilities integrated on a single PCB or in modular platforms, ideally with a small form factor and lower power consumption. An MCU, ASIC, or FPGA can be used to provide some processing power, and non-volatile memory is used to store digital sensor data.
3D printing is expanding the applicability of embedded sensors into new areas that are difficult to reach with COTS sensors. Companies like Phytec and Harris Corp. have additively manufactured, sensors, antennas or cutting-edge electronics with lower cost, lower fabrication time, and/or performance that competes with COTS components.
As 3D printing technology continues to advance, so will the range of available embedded component or transceiving applications. With this in mind, let’s look at three interesting uses of embedded sensors that might inspire your next design:
3D-Printed Embedded Sensors for Robotics
Embedded sensors are not only relegated to use in sensor networks, although this is one area in which 3D printing allows fabrication of low-cost sensors with a unique shape and size. In the area of soft robotics, the synergy between embedded sensors and 3D printing is giving way to unique robotic systems that can be fabricated entirely using additive manufacturing.
At Harvard’s Wyss Institute, researchers have developed 3D-printed embedded sensors for controlling a soft robotic hand. This system uses 3D-printed pressure, curvature, and inflation sensors as part of a feedback loop to control how the hand grasps objects.
These sensors are printed directly into the fingers of the robot and are purely resistive sensors. As the fingers flex while grasping an object, each conductor deforms slightly and its resistance changes, providing a simple way to monitor and control a robotic hand for grasping small objects.
Networking Topologies for Wireless Embedded Sensors
Many researchers and engineers are investigating new architectures, fabrication techniques, and applications for embedded sensor networks. These embedded systems must contain some wireless capabilities to send data to a base station.
One important area of research focuses on developing network topologies and adapting these sensors to existing and new communication protocols (e.g., Bluetooth, ZigBee, Z-Wave, and others). In particular, ZigBee is an excellent protocol for use in embedded sensor networks as it is adaptable to point-to-point, multi-point, and mesh network topologies with low power consumption.
Complementing 3D-printed embedded sensors with COTS sensors allows designers to build sensor arrays with greater functionality. 3D printing embedded sensing elements can allow data collection with a sensitivity that is comparable to COTS sensors while saving board space, reducing required assembly steps, and overall manufacturing costs.
Creating these sensor arrays with additive manufacturing allows antennas to be printed alongside embedded sensing elements. These wireless embedded sensor arrays can then be used to build a sensor network that collects massive amounts of data.
COTS devices complement embedded sensors and 3D printing. This CMOS photosensor could complement embedded sensing elements.
Wireless embedded sensors for military and aerospace applications require an additional layer of physical security. These devices are vulnerable to tampering and even counterfeiting when they are sent to an external manufacturer for fabrication. Keeping an additive manufacturing system in-house is just one of many security measures companies can take to ensure their capabilities are not exposed to a malicious party.
Embedded Sensors for Human-Machine Interaction
As IoT devices and other technologies become “smarter,” 3D printing will enable new methods for human-machine interaction (HMI). Although the history of non-mechanical HMI spans nearly three decades, new electronic fabrication techniques have already revolutionized electronic and optical HMI technologies.
For example, touch screen technologies were purely resistive, and an applied force was required to make contact between crossed grids of transparent electrodes. Nowadays, capacitive touch sensors allow a human finger to be distinguished from other objects that might make contact with the sensing element. Using an additive manufacturing system based on conductive nanoparticle inks also allows capacitive touch sensors to be placed directly on a 3D printed PCB with a layer-by-layer printing process.
Placing embedded sensors with 3D printing directly onto PCBs allows these sensors to be placed in wearable devices for HMI applications. For example, these devices can be placed into a glove, as was recently published in Advanced Materials Technology. This allows hand motions to be measured and tracked in real-time. The embedded passive components and MCU allow data to be gathered and processed, and the embedded antenna can be used to send this data to a nearby computer.
Rather than working with COTS sensors, fabricating embedded sensors with 3D printing offers designers broader capabilities compared to COTS components. 3D printing of embedded sensors facilitates new applications that are simply not practical with COTS sensors.
While applications of 3D-printed embedded sensors are still in the proof of concept phase, the initial results are very promising and will continue to build on existing 3D-printed sensor applications. We look forward to seeing more advances in these areas in the near future.
If you need rapid prototyping capabilities for new sensor designs, look no further than the DragonFly Pro additive manufacturing system. Sensor engineers can quickly produce novel 3D-printed sensors alongside other functionality on a single PCB. Read a case study or contact us today if you’re interested in learning more about the DragonFly Pro system.