Your Contact to Sensirion

Umschlag

Contact

Contact our sensor experts:

Contact Form

Distributoren

Distributors

Here you find the nearest distributor in your area:

Our Distributors

Standorte

Locations

Find out where we are located:

Our Locations

toggle menu
  • Home
  • News
  • Sensirion Products
    • SEK-SensorBridge (Evaluation Kit)
    • SEN5x Environmental Sensor Node
    • SCD4x CO2 Sensors
    • SFA30 Formaldehyde Sensor Module
    • SGP41 VOC+NOx Sensor
    • SGP40 VOC Sensor
    • SHT4x Humidity and Temperature Sensors
  • Partner Spotlight
    • Partner Spotlight SparkFun
    • Partner Spotlight MikroElektronika
    • Partner Spotlight Seeed
  • Archive
    • Platforms
      • Environmental Sensor Shield
      • Smart Gadget Development Kit
      • Wearable Development Kit
      • Raspberry Pi
      • Qualcomm Snapdragon
      • Arduino
      • Cypress PSoC Series
      • Generic Linux Support
      • Thingstream MQTT IoT Sensor Starter Kit
    • Applications
      • Sensors for Ventilation
      • CO2 Monitor Reference Design
      • SHTC3 BLE Beacon Development Kit
      • Directional Wind Meter Using SDP3x
      • Smart Speaker
      • Archive
    • Labs
      • #21 - Using an RJ45 Breakout Board Connect with Evaluation Kit Cables
      • #20 - Integrate Flex-PCB Sensors into Prototyping Setups
      • #19 - Smart Factory Particle Monitor Network
      • #18 - Inhalation Application Benefits
      • #17 - Sleep Analysis and Pulse Monitor
      • #16 - Thermal Comfort Sensor
      • #15 - Anti-Fogging for Bathroom Mirrors
      • #14 - Improved Puff Sensing of Inhalation Devices
      • #13 - Spirometer
      • #12 - Breath Detection
      • #11 - Stress, Mood and Emotion Sensing
      • #10 - CO2 Sensing in Car
      • #9 - Milk Fat Concentration Sensor
      • #8 - Presence Detection with IR Sensor
      • #7 - RH Sensor Trigger for BLE Beacon
      • #6 - Smart Inhaler
      • #5 - Windshield Ice Detector
      • >> See All Labs Ideas
    • Tutorials
      • Wearable Development Kit: Build Your Own Device
      • Wearable Development Kit: Logging Data
      • Raspberry Pi: SFM Software Package
      • Raspberry Pi: Alexa with Indoor Air Quality
      • Raspberry Pi: Using Flow Sensors
      • Raspberry Pi: Weather Station
      • Arduino: Create Your Own CO2 Monitor
      • Arduino: Stand-Alone Liquid Flow Meter
      • Arduino: Interface for Liquid Flow Sensors
      • Arduino: Weather Station
      • Arduino: Closed Loop Volume Controller Using Liquid Flow Sensors
      • Arduino: Interface for Multiple SF06 Liquid Flow Sensors
      • Arduino: Interface for SF06 Liquid Flow Sensors with Level Shifter
      • Arduino: CAN Bus Flow Meter
  • Global Website

Contact

search
cart
DOWNLOAD CENTER BUY NOW INVESTORS
Sensirion AG Switzerland
  • Home
  • News
  • Sensirion Products
    • SEK-SensorBridge (Evaluation Kit)
    • SEN5x Environmental Sensor Node
    • SCD4x CO2 Sensors
    • SFA30 Formaldehyde Sensor Module
    • SGP41 VOC+NOx Sensor
    • SGP40 VOC Sensor
    • SHT4x Humidity and Temperature Sensors
    • Sensirion Products

      Start testing our sensors

      Here you can find all information for evaluating and testing Sensirion's latest sensor solutions. From drivers and software to tutorials and quick start guides - we try to offer all tools necessary so that you can kick-start your application!

  • Partner Spotlight
    • Partner Spotlight SparkFun
    • Partner Spotlight MikroElektronika
    • Partner Spotlight Seeed
  • Archive
    • Platforms
      • Environmental Sensor Shield
      • Smart Gadget Development Kit
      • Wearable Development Kit
      • Raspberry Pi
      • Qualcomm Snapdragon
      • Arduino
      • Cypress PSoC Series
      • Generic Linux Support
      • Thingstream MQTT IoT Sensor Starter Kit
    • Applications
      • Sensors for Ventilation
      • CO2 Monitor Reference Design
      • SHTC3 BLE Beacon Development Kit
      • Directional Wind Meter Using SDP3x
      • Smart Speaker
      • Archive
        • On/Off Body Detection
        • Perspiration
        • Antifogging in VR Goggles
    • Labs
      • #21 - Using an RJ45 Breakout Board Connect with Evaluation Kit Cables
      • #20 - Integrate Flex-PCB Sensors into Prototyping Setups
      • #19 - Smart Factory Particle Monitor Network
      • #18 - Inhalation Application Benefits
      • #17 - Sleep Analysis and Pulse Monitor
      • #16 - Thermal Comfort Sensor
      • #15 - Anti-Fogging for Bathroom Mirrors
      • #14 - Improved Puff Sensing of Inhalation Devices
      • #13 - Spirometer
      • #12 - Breath Detection
      • #11 - Stress, Mood and Emotion Sensing
      • #10 - CO2 Sensing in Car
      • #9 - Milk Fat Concentration Sensor
      • #8 - Presence Detection with IR Sensor
      • #7 - RH Sensor Trigger for BLE Beacon
      • #6 - Smart Inhaler
      • #5 - Windshield Ice Detector
      • >> See All Labs Ideas
    • Tutorials
      • Wearable Development Kit: Build Your Own Device
      • Wearable Development Kit: Logging Data
      • Raspberry Pi: SFM Software Package
      • Raspberry Pi: Alexa with Indoor Air Quality
      • Raspberry Pi: Using Flow Sensors
      • Raspberry Pi: Weather Station
      • Arduino: Create Your Own CO2 Monitor
      • Arduino: Stand-Alone Liquid Flow Meter
      • Arduino: Interface for Liquid Flow Sensors
      • Arduino: Weather Station
      • Arduino: Closed Loop Volume Controller Using Liquid Flow Sensors
      • Arduino: Interface for Multiple SF06 Liquid Flow Sensors
      • Arduino: Interface for SF06 Liquid Flow Sensors with Level Shifter
      • Arduino: CAN Bus Flow Meter
Sensirion AG Switzerland
  • On/Off - Body Detection

     

     

  • Sensirion Developers
  • Archive
  • Applications
  • Archive
  • On/Off Body Detection

On/Off Body Detection

On/off body detection is about detecting whether a device is worn on the human body or not. This function can be implemented with Sensirion’s humidity sensors and offers various new use cases.

The propagation of smart features like noise cancelling, wireless connectivity and fitness tracking functions into headphones and other wearables alike is a hot topic in the industry. The information if a headphone is taken off while connected, allows the smartphone to pause the music and put on a loud ringtone rather than just ringing via headphones. Furthermore it enables smart battery management according to the user’s individual needs. Besides headphones, the on/off body detection feature is also applicable for other battery-driven devices like VR goggles, smart watches, fitness trackers or wearable medical devices.

Advantages of Using a Humidity Sensor for On/Off Body Detection

  • Suitable for all form factors
  • Contactless measurement
  • Very reliable (can distinguish between human presence and object presence)
  • Off the shelf product
  • Cost efficient
  • Low power consumption
  • Provide environmental data

Recommended sensor: Humidity sensor SHTW2


On/Off Body Detection - Implementation

Working Principle

  • Measurement of environmental humidity and temperature conditions
  • Determination of human presence via environmental changes caused by the human body
  • Signal processing and feature extraction techniques to detect state changes

Implementation Concept

  • Skin aware and ambient aware sensor integration
  • Sensirion headphone example demonstrating potential sensor integration

On/Off Body Algorithm

The humidity and temperature sensor measures the environmental conditions in its vicinity. Any object with a different temperature or humidity (e.g., due to perspiration), which gets close to the sensor influences the values measured. With a device integrating a humidity and temperature sensor in a way that it is close to the human skin when worn can detect these variations and process them to deduce whether the device is on body or off body.

This is visualized below on a real world data set. The solid red curve describes the humidity signal measured by a Sensiron SHTW2 humidity sensor integrated in an in-ear headphone (as depicted above). When the headphone is worn, the humidity signal increases compared to the ambient humidity conditions visualized with the solid blue line below. With signal processing and feature recognition algorithms, we can create a reliable binary signal depicting whether the device is on body or off body (green line below).


Algorithm Description

This is a high level description explaining the fundamentals of an easy to understand on/off body detection algorithm. Please refer to the source code for a more precise version of the algorithm. To further improve your product in various environmental conditions you can refer to other feature detection techniques, as described further down in this tutorial.

Algorithm:

This is a simple threshold detection algorithm, as used in many other applications. The transpiration is computed for every subsequently read output of the ambient and the skin sensor and stored in an array of fixed length. To detect a state change from on body to off body or vice versa, a gradient threshold determination is used:

For relative humidity and temperature values measured at times T1 and T2, we compute the transpiration TRANS_T1 and TRANS_T2 and detect a state change as follows:

Formula to Calculate Transpiration

Corresponding signal plot

Transpiration at time T1: TRANS_T1
Transpiration at time T2: TRANS_T2 (T2 > T1)

if currentState == onBody {
    if TRANS_T2 - TRANS_T1 < -THRESHOLD
        currentState = offBody
} else {
    if TRANS_T2 - TRANS_T1 > THRESHOLD
        currentState = onBody
}
    
return currentState

Learn more about perspiration rate measurements, physics and use cases here.


Patent Information

Aspects of this application are protected by Sensirion patent(s) US 2016162256 A1 (pending), EP 2851001 A2 (pending), CN 105677012 A (pending) and/or other patents pending. For commercial licenses, please contact Sensirion AG.

For the sake of clarity, no rights are granted for uses without a Sensirion sensor. Neither the grant of a license under the patent(s) mentioned nor any other information or recommendation presented on this website do absolve you from the obligation of investigating the possibility of infringement of third parties’ rights and, if necessary, clarifying the position.


Follow Us

Sensirion Products

  • CO2 Sensors
  • Formaldehyde Sensors
  • VOC Sensors
  • Humidity and Temperature Sensors

Partner Spotlight

  • Sparkfun
  • MikroElektronika

Archive

  • Labs
  • Applications
  • Tutorials
  • Platforms

Further Information

  • Developer News
  • Download Center
  • FAQs
  • Contact
  • Locations

Your Contact to Sensirion

Umschlag

Contact

Contact our sensor experts:

Contact Form

Distributoren

Distributors

Here you find the nearest distributor in your area:

Our Distributors

Standorte

Locations

Find out where we are located:

Our Locations

Please Find Here Various Support Topics

Buy Our Products at Your Local Distributor

About Sensirion

Environmental Sensors

Flow Sensors

Media/Newsroom

Investors

Useful Links

Sensirion Automotive Solutions

Career

Support Center

Partner Access

General

Terms and Conditions

Terms and Conditions for US Customers

Supplier Social Responsibility

Quality, Environment and Ethics

Sensirion AG

Laubisruetistrasse 50

8712 Staefa ZH, Switzerland

Tel. +41 44 306 40 00

infosensirioncom

2022 © Sensirion AG Switzerland
  • Home
  • Sitemap
  • Privacy Policy and Cookies
  • Imprint
  • Login
  • Disclaimer