technology for graphene and fet-based sensorsprinted sensors the market for fully printed sensors is...
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Technology for Graphene and FET-based SensorsKrishna Persaud*1, Suresh Garlapati1, Sheida Faraji2, Michael Turner2,
Tien-Chun Yu3, Guohua Hu3, Jie Dai3, Tawfique Hasan3,Xiao Huang4
1Department of Chemical Engineering and Analytical Science, University of Manchester2OMIC, Department of Chemistry, University of Manchester
3Cambridge Graphene Centre, Engineering Department, University of Cambridge4Nanyang Technological University, China
Printed Sensors
The market for fully printed sensors is predicted to reach $7.6 billion by 2027.
www.idtechex.com
• Printed disposable glucose sensors currently generate the majority of revenues. • Gas sensors, temperature sensors and photodetectors are moving to mass production.• The next generation of printed sensors will enable new applications, from human-machine interfaces to environmental
sensing.
Source: IDTechEx
• Large area• Conformal• Wearable• Imperceptible • …
• Printed gas sensors play a key role in IoT development.
Printed Gas Sensors
NH3 sensor
Danesh, E., et al. Analytical Chemistry 86 (18) (2014) 8951Seekaew, Y. Organic Electronics 15 (2014) 2971–2981
Jung, Y. Sensors 17(5) (2017) 1182
• Ventilation and air conditioning (HVAC) systems, air purifiers and smart windows will employ gas sensors for air quality monitoring.
• Selective gas sensors are required for detection of atmospheric pollutants, e.g. VOCs, NOx, CO, ammonia, SO2, etc.
GraphClean – Air Quality Monitoring
200 mg/m3 of NO2 is 104 ppb and 40 mg/m3 of NO2 is 21 ppb PM2.5 sensor Gas sensor
10.8 mg/mL FeCl3+
1.66 mg/mL GO
120 ℃
8 h
sonication 60 min
wash with H2O and
IPA
53.3 mg/mL CH3COONa
Water + IPA (6/4 v/v)
redispersed in
IPA+2-butanol (9/1 v/v)
sonication
30 min
Metastable ink
Mass production of Fe2O3/graphene
Figure: Spray coated Fe2O3/graphene sensor arrays on (a) paper and (b)
polystyrene of a scale of A2 (420mm * 594mm). The array integrates 16 * 13
devices. The electrodes are screen-printed silver IDEs. The insets show zoomed-in
images of the sensors.
ba
5mm5mm
Large scale sensor prototyping
Inkjet printed graphene/metal oxide gas sensors on flexible substrates
Metal
electrodes
Connected sensors for environmental monitoring:
Low power, low cost, acceptable accuracy
With Prof X Huang, NTU
500 nm
a
500 nm
c
200 nm
f
200 nm
500 nm
200 nm
b
d
e
G. Hu et al, unpublished.
Inkjet printed graphene/metal oxide gas sensors
0 50 100 1500.0
0.4
0.8
1.2
Time (min)
Resis
tance (
a.u
.)
NO2
N2
0.2
pp
m
0.4
pp
m
0.6
pp
m
0.8
pp
m
1.0
pp
m0.0 0.4 0.8 1.2
0
5
10
15
20
Re (
%)
Concentration (ppm)
20.2%/ppm
Room temperature operation
With Prof X Huang, NTUG. Hu et al, unpublished.
Inkjet printed graphene/metal oxide gas sensors
12
34
5
1 2 3 4 5 6 7 8 9 10
Devic
e
Device
0.000
20.00
40.00
60.00
80.00
100.0
Re (%)
0 50 100 1500.0
0.4
0.8
1.2
Time (min)
Re
sis
tan
ce (
a.u
.)
NO2
N2
0.2
pp
m
0.4
pp
m
0.6
pp
m
0.8
pp
m
1.0
pp
m
80 85 90 95 1000
10
20
30
40
Co
unt
(%)
Re (%)
m: 89.1
s: 2.21
23
45
1 2 3 4 5 6 7 8 9 10
De
vic
e
Device
0.000
20.00
40.00
60.00
80.00
100.0
Re (%)
0.0 0.4 0.8 1.20
5
10
15
20
Re
(%
)
Concentration (ppm)
20.2%/ppm(a) Typical measured response under exposure to NO2for thestabilised response after intialsaturated exposure.
(b) The measured response in (a) with respect to the NO2 concentration, showing a sensitivity of 20.2%/ppm.
(c) The measured saturated responsivity of 45 devices of the sensor array. The 5 grey spots correspond to the short-circuited devices.
(d) Gaussian fitting of the measured initial saturated responsivity at 1 ppm N02, showing that 100% are distributed within μ±3σ.
Fitted mean (μ) response: 89.1%, Std dev (σ): 2.2
With Prof X Huang, NTUG. Hu et al, unpublished.
Connected gas sensors
Measurement on an OFET
Situation 5 years ago
Requirements:
• Solution processible to allow large-area production and easily customised sensor arrays.
• Low-voltage operation (< 3 V), low power consumption, integration with silicon microcontroller and portability.
• Good stability and durability (against bias stress, temperature, etc.).
• Sensitivity and Selectivity to a range of analytes, such as VOCs, ammonia, CO, NO2, SO2, etc.
Organic field-effect transistors (OFETs) as sensing platform
Chemiresistor→change in resistance
OFET→Multiparametric outputs,better sensitivity through amplification of current
L. Torsi and A. Dodabalapur, Anal. Chem., 2005, 77, 380A; Wedge et al. Sensors and Actuators B 143 (2009) 365Gromski, P. S. et al. Anal Bioanal Chem 406 (2014) 7581
• High-k dielectric: P(VDF-TrFE-CFE)
• Low-k capping layer: UV-crosslinked PMMA
• Organic semiconductor: DPPTTT 𝑪𝒊 =𝜿
𝒅
PEN
Gate
Dielectric
S DOSC
Fabrication of OFETs
P(VDF-TrFE-CFE) terpolymer:
• High κ (~ 55) due to ferroelectric phase and polar nanodomain.
• However, its polar surface groups tend to trap carriers from the channel or Interaction with water molecules and results in poor device stability.
Stability of OFETs against ‘bias stress’ and ‘temperature’
-500 0 500 1000 1500 2000 2500 3000 3500 4000
-50
0
50
100
150
200
250
300
350
400
450
Time (Sec)
Uncapped Terpolymer
I DS c
han
ge
(%
)
100% increase in IDS
Non-polar capping layers
0 1000 2000 3000 4000
0
500
1000
1500
2000
2500
3000
3500
<100% increase in IDS
Uncapped Terpolymer
PAMS-capped Terpolymer
PMMA-capped Terpolymer
I DS c
hange (
nA
)
Time (sec)
Dipole field induced localisation of charge carriers and interaction with water
molecules is suppressed.
Improve sensitivity and promote selectivity
Sensitizers as additives to OSC (DPP) solution
(a) Zinc Phthalocyanine (ZnPc)(b)Zinc 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (TTB-ZnPc)(c) Iron phthalocyanine (FePc)(d) 5,10,15,20-Tetraphenyl-21H,23H-porphine copper(II) (CuTTP)(e) and (f) phthalocyanine (Pc1 and Pc2)
Selectivity of semiconductorto different volatile analytes achieved by addition of smallamounts of compoundsthat promote specific analyteinteractions
GraphClean- Improve sensitivity and promote selectivity using sensitizers
Porphyrins
M: metal or empty
Phthalocyanines
-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0
10-12
10-11
10-10
10-9
10-8
10-7
10-6
IDS
IGS
I1/2
DS
I DS, I G
S (
A)
VGS
(V)
0.0
0.1
0.2
0.3
0.4
0.5
0.0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0
0.00
0.05
0.10
0.15
0.20
0.25
-1V
-2V
-3V
I DS (m
A)
VDS
(V)
-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0
10-11
10-10
10-9
10-8
10-7
10-6
10-5
I DS, I G
S (
A)
VGS
(V)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
IDS
IGS
I1/2
DS
0.0 -0.5 -1.0 -1.5 -2.0
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0V
-0.5V
-1V
-1.5V
-2V
I DS (m
A)
VDS
(V)
Limit of Detection (LoD ~ 20 ppb)
Nitrogen dioxide (NO2)
Limit of Detection (LoD ~ 20 ppb)
Carbon monoxide (CO)
GraphClean – Response to NO2, CO and mixtures
For detection of a certain gas, OFETs with specific recognition element (e.g. metal/metal-free phthalocyanine) can be used.
First NO2 /CO Sensor Module based on Organic Field Effect Transistors
Patented
GraphClean – Field trials in Manchester
UMAN
UCAM
Display Gas inlets
Front view Back view
Connected gas sensors
Manufacturability and device-to-device
consistency is key
Insi
de
offic
e
Insi
de
offic
e
Graphene/Metal oxide Chemoresistors
GraphClean – OFET Devices-Field trials in Manchester
NO2
For all sensors, correlating peaks in NO2 concentration are detected
around evening and morning rush hours .
Two sensor technologies with promise
• Graphene based chemoresistors and Low voltage printable gas sensors based on Organic Field Effect Transistors
• First OFET NO2 and CO Gas Sensor
• Good correlation with conventional environmental gas monitoring systems at a fraction of the cost
Acknowledgements: Innovate UK, EPSRC Centre for Innovative Manufacturing in Large Area Electronics, Partners University of Cambridge, Imperial College London, The University of Manchester, Swansea University
Conclusions