How Environmental Sensors Work
Environmental sensor use is expanding as organizations seek to measure and be alerted on air quality, temperature, humidity, particulate matter concentration, vape, sounds, gases concentration, etc. But how do these sensors work?
In this tutorial, IPVM examines the most common parts of environmental sensor units, including technology and different types of sensors. The environmental sensor components covered in this tutorial include:
- Temperature sensor
- Humidity sensor
- Carbon monoxide detector
- Air quality sensor
- Sound detector
- Particulate matter sensor
- Volatile organic compounds (VOC) sensor
- Gas sensor
This tutorial omits vape detection, as we covered this in-depth here: Vape Detectors Tutorial.
For background, see IPVM's tests of environmental sensors:
- Halo Smart Vape Detector 2.0 Tested
- Cisco Meraki Environmental Sensors Tested
- Soter FlySense Vape Detection Tested
- Verkada SV11 Environmental Sensor + Dashboard Tested
- Rhombus E2 Environmental / Vape Sensor Tested
Air ******* *****
*** ******* ***** ** * ****** used ************** ** *** ******* *** that ***** *** "***** ** ******** the *** **, *** **** ********** health ******* ***** ** * *******", per ******, *** ** ** ***** ********* by ************* *******.
*** ** ********** ** **** ****** and ******* *** (**** ******* ********* often ******* **) *** *** *** reading ***** *** * ********** ***** (i.e. **) *** * *********** ***** (i.e. "*********"), ** ***'* ***** ***** below:
*** ******* ** ********* *******, ********* the ************* ** ********** **** ** particulate ****** (**), ******** ******* ********* (VOC), *** ************* ** *****, ****** dioxide, ***. **** *********, **** ** Meraki,**** **** **** ******* *********** *** humidity.
** ********* ***, *** *** *** a *** ******* *** * ********* table, *** ***'***** **********. ************* ******* ******* ** *** then ***** * ****** ***** ** determine *** ***** *********** (** = AQI):
** ***** ****, *** ************ ** Halo *********, ********* ** **** **** they *** *** ******* ***** *** AQI ***********.
***** *** *********** *** *** "***** of * *********" ** ****, *** compares *** ******* **** * *********** scale (*.*. "****", "********", "*********", ***.).
****** **** ********** **********, ***** *** dependent ** ******** ******* (*** ********, buoyancy *****, ***.) *** ******* ***** contains **** **** ******* ** * single ******** (** **** **** ****** pollutant, *** *******, ** *************). ** one *** ************ *** ******** ********** (for *******, *** *** ****** ******* concentrations), **** **** ******* *** ** be ******* ******** *****, **** *** each *********.
** *** * ***** *** *******, one *** ** **** *** ******* outcome (*** ****** *** ******* ***** of *** *****, *** ***** *** air *******). ** **** ****, *** also ********** *** "*********** *********"—*** ********* with *** ******* ******* ***** *** its *****.
*** ******* ***** ********* **** *** would ** ** ******** ********** *** measured:
**** * ****** ********* *********** **** suffice *** *** ******* **********. *********, the ******** ** *** ******* ********* below (****** *** *** ***** ********) can ** **** *** *** ***********.
********* ************* ******* *** ******** ********* AQI ****** ********* ******* ******* **** in ***** ************ **** *** *********. For *******, ****** **** ** *** tech ************* **** ** **** ***********, humidity, ****, *** ***.*, ** ***** below:
Temperature *******
**** ******* ***** ** ***********/****** ** capacitors *** ****** **** ** ************* sensors *** ** ***** ***** ****, inexpensive ************* *****, *** ******** ********.
**********-***** ******* **** ** *** **** that "******* *******" ** *** ****-******* junction ** * ******* ************ ***********-*********. *** ********** ** *** ****-******* voltage *** *** *********** ** ****** which ********* *** **** ** *********** and ********, ******** ** * ***-****** dependence.
*** *** ***** ***** *** * better ************* ** *** *********** ****:
*********, * ******-**** ***** ************ ** sensors,**** *********** ******* ** **** ****. ******, ** *** ***** ****, told **** **** **** *** ********** sensors *** *********** ***********, ******* ** transistor-based.
********** *********** ******* *** ***** ** the******* ********* ** *** ********** ************** *** ****** ** *** ********* that ******* *** *********** *** ********* the ***** ******.
*** ********** ******** *** * ******* structure *** *** ******* ********* ************ for ********* ****** *** ****. ****, when *** *********** *******, *** ********** material ***** "******* ** ******** ** temperature ********* ** *********", *****, ** turn, ***** ** *** ****** ** the ***********.
******* ************* ** ********** *********** ********** ******** ******** ** ******* **. al.: **** **** ******** ****** **** have * **** ***********-********* *********** *** a ********** ******** **** ***** *********. Temperature ******* ***** ************ ** ***** plates *** *** ** *** ********** film, ** ***** *****:
*** ************ ****** *** *********** *** therefore *** ****** ******. *** *********** is ********* ***** ** *** *********** in *** ****** ******.
Humidity *******
********** *** ********* ******** ******* *** two ** *** **** ******** **** humidity *******. **** *** **** **** from ************** *** **** *** ***** in ****, ******* ** *********** *******.
********** *** ********* ******** ******* **** the **** ********—********* *** ******** ******** of *** ***.
*** ******** ******** ** *** ***** of *** ****** ** ***** *** holds ** *** ******* ***** ** vapor **** *** *** **** ** that *********** (** *** ******* ** passed ** ****** ***** ***** ********* to ****** * ***** ***** ** water ********* *** ****** ** **** to ***%).
Resistive **. ********** ******** *******
***** *** ******** ********* ******* ***** capacitive *** ********* ******** *******, **** as ********* ******** *****, ********, *** sensitivity ** ***** ********* ** *** air.
********** ******** ******* ******* ********* *** ******* **** ******** results. ********* ********** ********** *********** ** ************* *** ***** chemical ****** ** *** *** **** can ******** *** ******** *** *** a ******* ** ******* ***** **** capacitive *******.
********** ******* ******* ****** ******* ****** *** ** ***** **** confirmed ** **** **** **** *** using ********** ******** *******.
Capacitive ******** *******
** *** **** *******, *** ********* is *** **** **** ** ********** humidity *******.
*** ******** ****** ******** ** *** electrodes, *** ** ***** ** ****** and ******** ********* (** ** ****** on *** ** *** ********** ********). The ***** *** ** ****** ********** the ********** ******** *** ******** ** the **** (**** *** ** ***** or *******), *** * ********** ******* film **** ****** **** ******* ******* it, ** ***** *****:
**** *** ******* **** ******* *** moisture, *** ****'* ******* ********** ******** (the ******* ** ***** ******** ******) rises, ******* *** ********** ******** ** water *********** ** ***** ~* **** **** of ******* ** * *** *****.
** ******** ** *** ********** ******** leads ** ** ******** ** *** capacitance ** *** *********, ***** ******* the ***** ****** ** *** *******. These ******* ***** *** ** **** to ********* *** ******* ********.
Resistive ******** *******
********* ******** *******, ******* ** ***** capacitive ************, **** ******* *** ********** characteristics ** * **** ** * circuit, *******, **** ******* ********** *** not *********** ** ********* *** ********.
***** ******** ******* **** * ******* structure **** * **** ***** ** water-absorbing ******* ***, ****** ** ********** sensors, **** ******** *** ******* ******* through ******.
*** ********** ** *** ******* ******* because **** *** ***** ** ******** by *** ******** *************** (******* ** **** ******* ******* it) ************ ** ***** ***** * **** conductor ** ***********. ** ******** ** conductivity ***** * ******** ** *** resistance, *** *********, ******* ** *** output ******.
Sound ******** *******
*** ******** ** ************* ******* (********* Halo *.*, ********, ****, *** ****) are ******** **** * ***** ******** that *** ** **** ** **** facilities, **** *******, *** *** ********* of ****** *** ******** ** *********.
*** **** ***** **** ** * sound ******** ** * ***** ******** microphone, ***** ********* ***** ***** ****** from *** **** *** ***** ******** them ** ********** ******* *** ******* analysis. *** ********** ******** ***** ******** waves ** ********** ******, ****** * speaker, *** *******, ***** **** *** exact ********.
* ***** **** ** * ******** wave **** ********** ** *** *** and ** ****** ** * ********** displacement ** ********* ** *** ***, thus ******** ***** ** **** *** low ********. **** *** ***** **** hits * *******, ** ****** ** move **** *** ***** **** *** sound ****.
** ******** ********** ** * ********* with *** *** ***** **** *** vibrate **** *** ***** **** **** it, ****, ******** *** ******** ******* plates:
*** ****** ** **** ******** ****** the ****** ** *** *********** ** the ********* ***** ***** ** *** change ** *** ****** *******.
*** ******* ***** ***** * ***** detector,***** *** ***** ********, **** ** **** ** *****'* FlySense **** ********:
Electret ********** **. ******* **********
*******, *** *** *********** *** **********. A ****** ***** ******* ********** (*** one ** * *****) **** **** the ********* ** *** ** *** parts ** ******* ******** **** ** an ********** ******, *******, * ******* microphone **** *************** ********* ** ** so.
** *** * ***** ******** **** moves **** *** **** ******* ** and ******* **** ********, * **** of **** ** ******** ** **. This **** ** ********* ** *** circuitry *** ***** ********* *** ******** field, ** ***** *****:
*** ******** ** *** **** ** wire ***** *** ****** ******* *** magnetic **** (*** ****** ** ******** field ***** ******** *** ****) ***, due ** *** ********* ** *************** induction, ******* ** ********** ******* ** the **** **** ** ***** **** to ******* *** ********* ** *** detect ***** ***** ** **. *** same ********* ** *************** ********* ** used ** ***** *********, *** *******.
******** *********** *** ******* ********* **** dynamic *********** ** ************ **** ***** detectors *** ** ***** ******* ****, lower ***** ***********, *** *** *****.
Carbon ******** *********
******* ** ***** *********, ****** ******** detectors *** ***** ***** ** ******** units. *******, ************* ******* ********* ******* dedicated ****** ******** ********* (*** *******, Halo ** ******** * ****** ******** detector).
*** **** ******** **** ****** ******** detectors*** ***** ** *** *************** ****, **** ****, *** ** ***** Corp ********* **** **** *** ***** this ****. **** ** * **** with *** ********** (***** ****** ********* to *** *******) ********* ** * conductive ******** (***********), ** ***** *****:
**** ******** ** ******* ** *** and **** ** ** ** ******* with ****** ******** *** ************ ** this ******** ***** *** ******* ******. The ******** ** *** ******* ** directly ************ ** *** ************* ** the ** ** *** ***, ***** one *** ******** *** *************.
***-***** *******, ******* **** ** ** sensor, *** ***** ** * ******* principle. *******, ******* ** ************, ***-***** sensors *** * **** **** ** metal ******.
*** ** ************** *** ********* ** ***** *** sensors ** *************** *******. *** ******* *** ******* *********** (other **** ** ***** *** ****** the *******), *** ****** ***** *********** than ** *************** ****. *** **** sensor, ** *** ***** ****, *** a ******** *********** ***** *** *** be ******** ** ******* ****** **** may **** *** ******'* ******* *** inhibit ***********.
Gas *** *** *******
**** ** *** ************* *******, **** as ******* ** *** **** **, offer *** ************ ** ******** *** concentrations (*.*. ***, ***) *** *** sensors **** **** *** ** **** for ******** ******* ******** (***) ************.
*** ******** ** *** *** ******* are ***** ***** (***) ******* ** chemiresistors. **** *************, **** ** *******,******** ***** *** ******** **** **** "********* ***** ***** (MOx) *************."
*** *** ******* *** ***** ** the *** ********** ********* **** **** to ******* ** *** ********** ********** of *** ****. *** *** ****** consists ** (*) * ******, (*) sensing ****, *** (*) * ******* board, ** ***** *****:
*** ****** ***** (*.*., ***** *** concentration ** ***** *** ** ****** to *******) *** ** ******* **** groups: ******** (*.*. **, ***, *******, propanol, ***.) *** ********* (*.*. **, NO2, **, ***.). ***** **** ***** groups ******** *** ****** *** ****'* resistance ** ********* ****: ************* ***** ****** *** ********** ** the ***** *****, ********* **** ********:
********* ***** *** ********** ******** **** the **** *** ******** ********* ****** an ******** ********* ***** (*.*. ***** with ***** **** *********, **** ** the **** ** *** ********). ****, the ****** ** ********* **** *** take **** ** *** ******* *********, and ********** *********.
******** ***** ******** **** *** **** through ******** ******. **** * ******** gas (*** ******* ******* -* ****** **** ** **** *******) ***** ** ******* **** *** film, ******* ** ********* **** *** film, ** ******** ** ****** *** frees ********* **** **** '******' ** oxygen. **** ********* *** ****** ** free ********* *** ********* *** **********. The ******* ***** ***** *** *********** with *** ******** *****:
*** *********** (*.*., **** *** *** measures) ** ** ********* ****** ** a ****** *** ***** ** ********* ** * ****** of ********* ****, **** ** ********* ******* ***********, varying *** *********** ** *** **** (i.e. ******, ***************, *** ****** **** other ******** ** ********* ** ******* composites), ********* ** ***** **. **. A ***** ************,**********, **** ******* ******** **** ******** independent ******** *** ********* *****, *** its*********.
********, *** *** **** **** ***********, different ***** *** ***** ************* ********* changes ** **********, ** *** ***** shows *****:
*** **** ******** **** ********* *** sensor ***** ******, ****, ********, *** ***** ******(****, ***, *** ***** *** ******** used *** ** *********, *** ******** for *** *********).
Particulate ****** ******
**** ************* ****** **** **** *** reviewed ** *** *** * ********* particulate ****** ****** **** ** **** primarily *** **** *********. ******* ********* *********** * ******** *********** ** ** sensors *** **** ** *********** ******.
************* ************ ***********, ********, *********, *****, and ***** ******* ******.
************, *** ******* *** ******** ** our **** ******** -************* ****** ******** **** - **********, Halo, ******, *******, *****, *******
** ********** ** * ***** ** on ********** ************. * ***** **** time ******* *** ******* *** ******** it *** ******* **** ************ ** seemed *****. ** ******* ** *** the ********, ***********, *********, ***.