Contact: Heejin Choi
Email: hjchoi2@etri.re.kr
Phone: +82. 42. 860. 4946
High sensitivity / high
selectivity MEMS
formaldehyde gas sensor
technology
2
TECHNOLOGY BRIEF
▣ Technology Overview
Formaldehyde gas sensor on MEMS heater
HCHO gas sensor, MEMS heater, high sensitivity, selectivity to HCHO
□ Keywords
MEMS heater
(1.5 x 1.5 mm2)
<Characteristics of MEMS formaldehyde gas sensor>
•
Monitor electrical resistance of elements depending on oxygen adsorption
change through gas oxidation / reduction on detected substances (metal
oxide)
•
Adsorption of oxidizing gas -> Decrease conductive electronics ->
Increase conductivity of detected substance (for p-type material)
•
Adsorption of reducing gas -> Supply conductive electronics ->
Decrease conductivity of detected substance (for p-type material)
•
Heating (150-300 degrees) is required for effective response of gas
oxidation / reduction on the surface of metal oxide.
•
Conventional bulk heaters composed of metal line on alumina consume
large amount of power. MEMS heater is developed for gas sensor
having low power consumption.
3
TECHNOLOGY BRIEF
MEMS formaldehyde gas sensor technology
▶ Specs of MEMS micro-heater
▶ Specs of high sensitivity / high selectivity of HCHO detected materials
• Power consumption: 10~15mW at 300 degrees
• Size of micro-heater die: 1 x 1 mm2
• Heating area: < diameter 100 um
• High sensitivity: 25% at 50 ppb HCHO
(HCHO concentration to maintain standard air quality, 100 ppm (USA), 80 ppb
(WHO/Japan/Korea/Canada))
• High selectivity: response to HCHO 1 ppm is at least 4 times higher than that of
others such as alcohol, benzene, acetone, ammonia, carbon monoxide, nitrogen
dioxide, and etc. under the same concentration
• Environmental sensor, gas sensor, air quality monitoring for outdoors and
indoors, weather station, IAQ (indoor air quality) system for vehicles, and etc.
▣ Technology Description
▣ Application Fields
MEMS microheater
(1.5 x 1.5 mm2)
<MEMS formaldehyde gas sensor>
< Formaldehyde detected substance
SEM image and selective gas sensor >
4
▶Competitive / substitution technology
• Figaro Inc. and AMS Inc. commercialized gas sensor using semiconductor
based bulk heater. Power consumption of 200 ~ 800 mW to operate gas
sensor.
• SGX sensortech Inc., Citytech Inc., and Senko Inc. commercialized electrical
chemical gas sensor, but its only limited to 6 months ~ 3 years of use.
• Optical gas sensor is specialized to sense hundreds to thousands of ppm
for specific gas such as CO2, CH4.
▶Excellence compared to competitive / substitution technology
▣ Outstanding Features
▣ IPR Status
Korean patent 2 applicable
Competitive
Technology
Excellence of new technology
Electrical chemical
gas sensor
§
Although electro chemical gas sensor has excel ent
selectivity, there are constraints of needing to use
electrode from expensive metal.
§
This new technology makes mass production of
highly sensitive/selective HCHO sensor possible
based on metal oxide materials and MEMS
technology
Optical gas sensor
§
Although optical gas sensor is very accurate, its big
size and high price makes it hard to use.
§
Miniaturized sensor having minimal size of 1 x 1
mm2 through this technology, can be applicable to
mobile device or loT device.
5
• Individual sensor (gas sensor, dust
sensor, UV sensor) and multiple
environmental sensor (temperature /
humidity sensor) base on
semiconductors to make MEMS and
nano technology. This helps develop a
low-priced, low-powered, high
performance, high credible, smal -
sized, and digital sensor.
• Air quality sensor technology is used
not only in monitoring the
environment, but also in other
industries such as automobile,
consumer electronics, processing
industries, and medical / health care.
• Global competitiveness is very weak,
but some smal firms have
commercialized some few products
such as chemical gas sensor.
• Figaro Engineering: Commercialized
the traditional Taguchi type sensor and
has the most shares in the
semiconductor gas sensor market.
Recently, low-powered product based
on MEMS micro heater has been
released.
• SGX Sensortech: Bought e2v社 to enter
not only electro chemical gas sensor
market, but also in semiconductor gas
sensor market.
• Not only Figaro engineering and SGX
Sensortech, which research
semiconductor gas sensors, but also
firms such as FIS, Honeywel , Siemens,
Aeroqual have actively researched to
produce products due to higher
demands to monitor air quality of
indoors / outdoors.
• Gas sensor based on semiconductors has been researched actively due to
advantages such as variety of detected gas, easy manufacturing, and large
market scale.
• Metal oxide sensing material is the most important factor of the sensor. N-type
semiconductor (SnO2, ZnO, TiO2, WO3, In2O3, and etc), of which electrons act
as charge carriers, has a fast reaction rate. P-type semiconductor (CuO, NiO,
CO3O4, and etc), of which holes act as charge carriers, is superior in operational
stability because of large amount of absorbed oxygen on the surface.
• One-dimensional nano-material such as wire, rod, tube, and ribbon for sensing
is being developed for high sensitivity, smal size, and low power.
• Although nano gas sensor based on semiconductor is recognized as the most
promising technology for the next generation gas sensors such as multi-gas
sensor, e-nose, there are many conflicts such as target gas selectivity,
environmental issues, operational stability that needs to be resolved for
practical commercialization.
□ Korea
□ Global
▣ Technology Trend
<Semiconductor Gas Sensor Material Research Status>
6
기술수요
적용처
• The whole gas sensor market is expected to
be $2.32 billion in 2018, and 20% is expected
to be semiconductor gas sensor. (Research &
Market, 2015)
• Compact / low-powered / low-priced MEMS
gas sensor entered the market in 2015, and
will expected to have $500 mil ion in 2017.
(IHS, 2013)
• The demand for compact / low-powered /
low-priced VOC (HCHO) gas sensor is
increasing rapidly, but a secure source of
supply has been difficult to find.
• World market for air purifier is expected to
increase 16% annual y from $3.8 billion in
2013 to an expected $9.2 bil ion in 2019.
(KISTI, 2015)
• An increase demand for gas sensor to monitor
air quality for loT service in smart home and
smart city.
Gas sensor is the number one
priority that needs to be developed than
proximity sensor, temperature sensor, or dust
sensor. (IHS, 2014)
▣ Market Trend
□ Market Leaders
Product name
Product
photo
Core technology
Efficiency
Note
MLV-P2 (Ams AG,
Austria)
• Semiconductor
• MEMS type
•
Various VOC nonselective detection:
alcohol, aldehyde, ketone, organic acid,
amine, aliphatic hydrocarbons etc.
•
Power consumption: 34mW (@320degree
celcius active)
•
Low reation time
•
H2 / selective of humidity
•
TO-39 header / 9x9mm2 PCB
•
No private ROIC
• Early stage of
commercialization
• Deliver wiggins
home monitoring
system
TGS8100 (Figaro,
Japan)
• Semiconductor
• MEMS type
•
Detect ethanol, H
2, CO, isobutane
•
Not selective of gas in low concentration
(~1ppm)
•
Power consumption: 15mW
•
3.2x2.5x1.0mm3
•
Ceramic package
•
No private ROIC
• Early stage of
commercialization
HCHO gas sensor
(Synkera, US)
• Semiconductor
• Bulk sensor
• (다공성) nano
detecting
material
•
Lowest detected 250ppb
•
Power consumption: 250mW
•
Not selective of CO gas
•
TO-39 package
•
No private ROIC
• Research
prototype
development
stage
HCHO gas sensor
(ETRI, Korea)
• Semiconductor
• MEMS type
• (다공성) nano
detecting
material
• Digital interface
•
HCHO lowest detected 60ppb
•
Power consumption: 15mW
•
Highly selective for ethanol and CO gas
•
Environment friendly (85 degree / 85%RH /
100h sensitivity change <10%)
•
Private ROIC
• Research
prototype
development
stage
• Commercialization
and
7
§
Low-powered MEMS heater manufacturing technology
§
Technology of Precursor production detecting formaldehyde
§
Heat treatment method of metal oxide for formaldehyde sensing
material
§
Paste formulation for formaldehyde sensing material
§
Highly sensitive / selective formaldehyde gas sensor
characteristics analysis
▶ loT environmental sensor
• Measure air quality in enclosed work
space: Use low-powered gas sensor to
wirelessly monitor harmful gases in water /
electricity / gas underground facilities.
• Safety management system in subway:
Measure air quality and dust level in
subway stations and provide the
information on electronic display.
• Air quality management for healthcare in
schools: Monitor air quality of classrooms.
Automatic ventilation when the air quality
is at a certain level to provide a healthier
and more comfortable learning
environment.
• Eco-friendly air purifier to prevent sick
building syndrome: Use highly selective
air purifier to prevent formaldehydes
caused by sick building syndrome from
new buildings, apartments, or furniture.
▣ Applications and Effects
▣ Scope of Technology Transfer
