Textile-integrated Motion Sensing in Seating and Lying Surfaces

Many people spend a large part of their everyday working life sitting down. The possible consequences are back pain, stiff neck or muscles due to the one-sided stress on the spine and muscles.

But how exactly do we sit and how should seating furniture be designed so that we can sit better and "healthier"?

Information such as the sitting position and movements of the seated person are acquired by the capacitive motion sensors integrated into the seating surface and backrest. Similar to a smartphone touchscreen, 72 sensors register every movement in real time. Textile-integrated, capacitive motion sensing combines inconspicuous sensor technology for capturing body movements with robust algorithms for mapping and interpreting movement behavior while sitting.

This capacitive motion sensor technology is integrated into the “Smart Chair” technology demonstrator created by Fraunhofer IIS.

“Smart Chair” users can choose between two operating modes

  • In analysis mode, the Smart Chair saves the captured data and calculates activity parameters offline to quantify the movements of the seated person.
  • In real-time mode, the system is used as a standardized input device to control the computer mousend can thus be used as a human-machine interface.

In both operating modes, the data is sent via Bluetooth to a computer, on which the weight distribution of the seated person can additionally be visualized by means of false color imaging.

Measurement Technique: Mutual Capacitance Sensing

Textile-integrated motion sensing
© Fraunhofer IIS
Screen interface of textile-integrated movement sensor technology from Fraunhofer IIS

Arranged in a matrix, the capacitive sensor fields respond with pinpoint precision to changes in the electrical field caused by pressure on the seat surface. To do this, the system employs the principle of mutual capacitance sensing, whereby the electrical capacity between two electrodes is measured for each sensor. The highly sensitive sensors register miniscule capacity changes in the measurement range of 4 pF with a resolution of 16 bits.

Possible Areas of Application

  • Capturing and interpreting movement behavior while sitting
    • Measures to prevent musculoskeletal disorders
    • Rehabilitation measures as incentive for physical movement
  • Use as real-time-capable human-machine interface
    • Assistance systems to support people with impairments
    • Serious gaming to promote motor and cognitive skills
    • Mobile gaming in vehicles and aircraft
    • Media control

Highly versatile, the miniaturized sensor technology and analysis electronics can be integrated into seating furniture, vehicle seats and lying surfaces. The low height of the sensors (approx. 0.5 mm) allows natural seating comfort, while their narrow design ensures that seating and lying surfaces remain breathable.

Technical Details

activity plot
© Fraunhofer IIS
Capacitive textile sensor system by Fraunhofer IIS calculates activity and movement sequences compared to a reference system. Here we see a high level of concordance.
  • Textile-integrated sensor fields
  • Sensor matrix with 72 independent capacitive sensors
  • Narrow, low sensor design (height: 0.5 mm)
  • Breathability in seating and lying surfaces
  • Real-time interpretation of movements to control computer mouse
  • Calculation of activity parameters to quantify movement behavior
  • Transmission of sensor data via Bluetooth

Note

The »Smart Chair« has not yet been certified as a medical product. Fraunhofer IIS is presenting the »Smart Chair« with the aim of engaging partners to further develop, manufacture and market it. 

More Information

Brochure

Communication. Sensors. Analysis.

Digital Health Systems

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