Progress and Future Challenges for 3D-Printed Sensors

By Benedette Cuffari, M.Sc.May 21 2020

Image Credits: Alex_Traksel / Shutterstock.com

The technologies behind both 3D printers and sensors have individually experienced substantial growth and advancement over the past several years. As researchers have discovered the advantages associated with the integration of these two technologies, it is crucial for them to also consider the future challenges.

Introduction to Sensors

A sensor is defined as a device that can detect an event or change that occurs within a given environment. Information is then sent to a computer for data collection and analysis.

Considerable advancements within the field of sensor technology have allowed these devices to become essential components of a number of industries, including aerospace, medicine, robotics and manufacturing.

This widespread use is largely attributed to the numerous advantages associated with sensors, such as higher productivity, precision and sensitivity, as well as their flexibility to be used for different purposes.

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The production of sensors can be achieved through several different manufacturing techniques, of which depend upon the type of sensor being produced. For example, the production of strain sensors can be achieved by lamination, coating and/or lithography.

An Overview of 3D Printing for Sensors

Over the past several years, additive manufacturing (AM), which is more commonly referred to as three-dimensional (3D) printing, has transformed a number of both industrial and academic applications. Through the use of this technology, users are able to produce geometrically complex parts at a much more rapid rate compared with traditional manufacturing processes.

When used for the fabrication of sensors, 3D printing offers several advantages, including lower costs, rapid fabrication rates and high accuracy. In addition to having the capabilities to intrinsically print entire sensors, 3D printing can be started or stopped at any point in the fabrication process, allowing users to easily embed a sensor into printed structures.

3D-Printed Sensors

3D printing technology has been successfully integrated into the design, development and fabrication of numerous types of sensors, some of which include force, strain, pressure, tactile, displacement, electromagnetic, electroencephalography (EEG), acoustic, optical, ultrasonic and biosensors.

Force Sensors

Force sensors function by measuring the displacement or strain of a flexure, which is an internal structural element, and converting these applied forces into measurable electrical signals. A force sensor is typically comprised of three parts: the flexure, transducer and its packaging.

Since force sensors must be capable of sensing multiple directions of torque, traditional manufacturing of these devices often requires complicated structures that couple multiple conventional sensors.

As a result, general-purpose commercial force sensors are either extremely bulky or have limited practical utility. Force sensors produced by 3D printing technology are inexpensive, easily customizable and can be produced at a much more rapid rate.

In fact, 3D printing allows users to tailor the configuration of a force sensor for specialized applications, such as medical devices, automotive components, musical instruments, robotics and computer input devices.  

Optical Sensors

One of the key advantages associated with incorporating 3D printing technology into the production of optical sensors is the ability to reduce all components of these sensors, such as the mirrors and lenses, into a single and simple printed sample.

One recent study found that 3D printing technology was successful in creating a lightweight and inexpensive fiber-optic vibration sensor that was specifically designed for use in high-power electric machines. In their work, the sensing mechanism was achieved by a blade, which had been attached to a bendable membrane, that modulated light intensity.

EEG Sensors

Electroencephalography (EEG) is a valuable diagnostic tool that neurologists use to evaluate the electrical activity of a patient’s brain. Recent advancements in EEG technology have allowed this crucial technology to be used outside of the clinical setting in the form of wearables that support epilepsy diagnosis and stroke rehabilitation.

Despite this progress, wearable EEGs can be destroyed when exposed to moisture and are also associated with other limitations, such as invasive electrodes that irritate the skin and poor long-term stability.

In an effort to overcome these challenges and improve sensor performance, recent work conducted at the University of Manchester found that 3D printers could successfully manufacture dry EEG electrodes with a higher noise floor that also do not require the use of conductive gel.

Compared with standard wet electrodes, the work conducted by these scientists found that their 3D-printed electrodes were inexpensive to produce and could also be easily optimized to fit the needs of each individual user.

Table 1: Different 3D-printing methods and the current types of materials available for their use.

Future Challenges

The 3D-printed sensors discussed here are just some of the numerous complex devices that have been easily created through 3D printing technology. Although this work is promising, considerable challenges within this industry continue to exist and limit future sensor production.

As demonstrated in Table 1, various types of materials can be used in different 3D printing methods. However, each 3D printing technique clearly has restrictions for which type of material can be used for fabricating a given sensor. Unfortunately, this limitation directly affects the performance and reliability of printed sensors in the event that an ideal printing method is available but incompatible with a specific material.

In addition to material availability, there remains a lack of information available on the durability and overall life cycle of 3D-printed sensors. While this challenge is largely attributed to the novelty of these sensors, future work must consider how each production step can contribute to shortening the lifetime of a printed sensor.

In addition to determining a sensor’s robustness, the role of 3D printing in a sensor’s life cycle will also determine whether this technology contributes to the growing amount of electronic waste or resolves it.

References and Further Reading

Khosravani, M. R., & Reinicke, T. (2020). 3D-printed sensors: Current progress and future challenges. Sensors and Actuators A: Physical 305. doi:10.1016/j.sna.2020.111916.

Xu, Y., Wu, X., Guo, X., Kong, B., Zhang, M., et al. (2017). The Boom in 3D-Printed Sensor Technology .Sensors 17(1166). doi:10.3390/s17051166.

“Force Sensing Applications” – Sensitronics

Krachunov, S., & Casson, A. J. (2016). 3D Printed Dry EEG Electrodes. Sensors 16(10). https://www.mdpi.com/1424-8220/16/10/1635doi:10.3390/s16101635.

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