EOS Additive Minds Manager Fabian Alefeld says the first prototype with its smart knee-joint monitoring shows the potential of combining AM with sensors and connectivity.
Photo: EOS & Blackbox Solutions GmbH

A smart knee prosthetic containing embedded sensors and connectivity allows doctors to analyze data in real-time, potentially speeding patient recovery. Additive manufacturing (AM) company EOS and Blockbox Solutions combined their respective expertise in 3D printing and sensor technology to create the customizable orthosis.

EOS officials say the full potential of Internet of Things (IoT) comes from leveraging AM, a technology that makes it easier to integrate intelligent and connected components. The combination of sensor technology, connectivity, and AM could expand digitization to new applications and business cases.

A recurring challenge

Torn ligaments, typically caused by wrong movements and excessive physical pressure on the knee, are one of the most common knee injuries and usually require a long recovery period with a risk of long-term disabilities. Recovery periods vary heavily based on the patient’s movement behavior. Putting too heavy a load on the knee too early can prolong recovery, as can not moving often enough. However, most patients don’t know what’s too much and what’s not enough. Feedback from a smart device could prevent overexertion or needless restrictions.

EOS Additive Minds specialists developed a knee orthosis to provide that feedback, working with sensor technology experts from Blackbox.

“We created a 3D-printed orthosis which can be customized and has integrated sensors and actuator,” explains EOS Additive Minds Manager Fabian Alefeld. “The orthosis, connected to a smartphone app, can now give live feedback via vibration actuator.”

A buzz warns patients when they are overexerting themselves, and the app stores the data, allowing patients to share recovery information with their doctors to guide treatment. Patients gain instant feedback when engaging in activities that could harm rehabilitation progress.

AM smart orthosis

Combining mechanical design elements with embedded electronics – microcontrollers, sensors, radio frequency (RF) connectivity – forms smart parts that could enable customized products. AM smart parts could enable:

  • Precision designs
  • Full customization
  • Integrated sensors for rapid production
  • Optimized end-user functionality
  • Rapid time-to-market
  • Fast ramp-up of small serial production
  • Agile production

The proof-of-concept, 3D-printed knee orthosis with integrated sensors, data processing capabilities, and RF connectivity demonstrates how stakeholders in a product’s ecosystem can gain real-time insight and benefits from sensor data.

“We measured the angular position of the orthosis joint,” Alefeld explains. “This can also easily be transferred into the total number of movements a day and therefore activity. In future developments, a load sensor or even an accelerometer would add additional significant data points.”

Initial system requirements came from interviews with direct and indirect orthosis users – patients, doctors, and end-equipment manufacturers. Users told developers what data and/or information would be helpful to improve patient experience and doctors’ ability to provide real-time care.

PHOTO: EOS & Blackbox Solutions GmbH

Feedback, security, recovery

The prototype led to an embedded solution that can retrofit legacy orthosis by printing customized housing replacements with designed-in sensors. Sensors that measure angle and force combine high precision with a contactless approach, simplifying integration. WiFi and Bluetooth Low Energy (BLE) communication empowers real-time monitoring and can be controlled by connecting the device to computer networks. A personal mobile device acts as a user interface and controller.

Data analysis on remote, secure servers accessed with a mobile app or directly on the device leverages the integrated embedded computer. Sensitive data can be securely processed locally to protect user privacy and data security. Information collected can be accessed, analyzed, and secured via interfaces tailored for different users.

With Blackbox Solutions’ embedded electronics and user-interface prototype, the EOS team is investigating customized design requirements to retrofit sensor housings to add functionality to legacy orthoses.

Battery powered sensor technology and connected software will let patients and doctors monitor progress in real-time and guide rehabilitation to individual patients. Ongoing data collection will provide equipment manufacturers with user insights and product performance data, allowing refinement and advancement of future designs.


This illustrates AM’s benefits to design, functional sensor integration, and rapid production of customized parts while optimizing functionality for users.

Blackbox Solutions GmbH