Journal: Polymers

Article Title: Smart Sensor Systems for Wearable Electronic Devices

doi: 10.3390/polym9080303

Figure Lengend Snippet: Wearable temperature sensors. ( a ) Image of a 4 × 4 temperature coefficient of resistance (TCR) sensor array after application to the skin deformed by pinching the skin in a twisting motion (scale bar 8 mm). ( b ) Temperature of the palm measured with an infrared camera (blue) and a sensor array (red, offset for clarity) during mental and ( c ) physical stimulus tests. Reprinted with permission from Ref. . Copyright 2016, Nature Publishing Group. ( d ) Schematic diagram and representative image of the stretchable graphene thermistors at twisted states (scale bar 1 cm). ( e ) Images of the stretchable graphene thermistor at 0% and 50% strains (scale bar 1 cm). ( f ) Resistance variation with temperature (30 to 100 °C) within 0% to 50% strains (step 10%). Reprinted with permission from Ref. . Copyright 2015, American Chemical Society.

Article Snippet: In an attempt to solve this problem, Choi et al. reported centimetre-scale transparent graphene sensors for nitrogen dioxide (NO 2 ) gas that had laterally-integrated or vertically-integrated graphene heaters on a polyethersulfone (PES) substrate [ ]. a shows a photograph of a transparent, flexible single-layer graphene (SLG) gas sensor with built-in, bilayer graphene (BLG) heaters. b shows that the temperature of the SLG sensor can reach 165 °C when the BLG heater temperature is 250 °C. c shows the recovery time constant ( τ r ) after using the heaters to apply different temperatures.

Techniques:

Journal: Polymers

Article Title: Smart Sensor Systems for Wearable Electronic Devices

doi: 10.3390/polym9080303

Figure Lengend Snippet: Wearable pressure sensors. ( a ) Cross-sectional schematic illustration of the pressure sensor and its connections to an associated transistor. ( b ) Photograph of the pressure sensor placed on a wrist and neck for measuring fast transients in the blood pressure (scale bars 1 cm and 2 cm). Reprinted with permission from Ref. . Copyright 2014, Nature Publishing Group. ( c ) Images of pressure sensor printed on the commercial elastomeric patch. The sensor array is composed of four channels of pressure sensors (scale bars 1 cm). Reprinted with permission from Ref. . Copyright 2014, John Wiley and Sons. ( d ) Photograph showing the skin-attachable sensor directly above the artery of the wrist (scale bar 3 cm). ( e ) Measurement of the physical force of a heartbeat under normal and exercise conditions. Reprinted with permission from Ref. . Copyright 2014, Nature Publishing Group. ( f ) Schematic image of pressure-sensitive graphene FETs with air-dielectric layers. ( g ) Plot of normalized drain current changes versus applied pressure. (inset indicates relative change in the field effect mobility under applied pressure). Reprinted with permission from Ref. . Copyright 2017, Nature Publishing Group.

Article Snippet: In an attempt to solve this problem, Choi et al. reported centimetre-scale transparent graphene sensors for nitrogen dioxide (NO 2 ) gas that had laterally-integrated or vertically-integrated graphene heaters on a polyethersulfone (PES) substrate [ ]. a shows a photograph of a transparent, flexible single-layer graphene (SLG) gas sensor with built-in, bilayer graphene (BLG) heaters. b shows that the temperature of the SLG sensor can reach 165 °C when the BLG heater temperature is 250 °C. c shows the recovery time constant ( τ r ) after using the heaters to apply different temperatures.

Techniques:

Journal: Polymers

Article Title: Smart Sensor Systems for Wearable Electronic Devices

doi: 10.3390/polym9080303

Figure Lengend Snippet: Wearable strain sensors. ( a ) Schematic illustration of the cross-section of the strain sensor consisting of the three-layer stacked nano hybrid structure of polyurethane-poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PU-PEDOT:PSS)/single-wall carbon nanotube (SWCNT)/PU-PEDOT:PSS on a polydimethylsiloxane (PDMS) substrate. ( b ) Time-dependent Δ R / R 0 responses of the sensor attached to the forehead when the subject was crying. Reprinted with permission from Ref. . Copyright 2015, American Chemical Society. ( c ) Optical micrograph of a graphene woven fabrics (GWFs)-PDMS-tape composite film (scale bar 0.1 mm). ( d ) Relative change of resistance between 0% and 0.2% strain. Reprinted with permission from Ref. . Copyright 2014, John Wiley and Sons. ( e ) Schematic illustration of stretchable capacitor with transparent electrode (top) and photograph of the same device reversibly adhered to a backlit liquid-crystal display (bottom) (scale bar 1 cm). ( f ) Change in capacitance Δ C / C 0 versus strain ε (top) and Δ C / C 0 versus time t over four cycles of stretching (bottom). Reprinted with permission from Ref. . Copyright 2011, Nature Publishing Group. ( g ) Schematic image of multicore-shell printing process for fiber-type capacitive strain sensor. ( h ) Normalized decay time output of the sensor for different walking speeds up to 4 mph. Reprinted with permission from Ref. . Copyright 2015, John Wiley and Sons.

Article Snippet: In an attempt to solve this problem, Choi et al. reported centimetre-scale transparent graphene sensors for nitrogen dioxide (NO 2 ) gas that had laterally-integrated or vertically-integrated graphene heaters on a polyethersulfone (PES) substrate [ ]. a shows a photograph of a transparent, flexible single-layer graphene (SLG) gas sensor with built-in, bilayer graphene (BLG) heaters. b shows that the temperature of the SLG sensor can reach 165 °C when the BLG heater temperature is 250 °C. c shows the recovery time constant ( τ r ) after using the heaters to apply different temperatures.

Techniques:

Journal: Polymers

Article Title: Smart Sensor Systems for Wearable Electronic Devices

doi: 10.3390/polym9080303

Figure Lengend Snippet: Wearable gas sensors and its integrated systems. ( a ) Photograph of transparent and flexible single-layer graphene (SLG) sensor channel-bilayer graphene (BLG) heater on a polyethersulfone (PES) substrate (scale bar 7 mm). ( b )Temperature distribution along transverse (x-axis) and longitudinal (y-axis) direction of sensor-heater device structured as laterally intercalated SLG sensor channel (6 mm width) between BLG heaters (7 mm width) with applied 1.7 W of electric power. Here the red dot and blue dot are temperature profiles of thermal image in inset along x-axis and y-axis with origin at center on channel, respectively. Inset: Spatial temperature distribution of graphene heaters (7 mm width) which intercalate 6 mm width graphene sensor with applied 1.7 W. Here three broken squares indicate center channel and side heaters area, respectively (scale bar 7 mm). ( c ) Recovering time constant τ r as a function of heater temperature. Inset: the recovering curves of the Δ R / R 0 as a function of time under different temperature range from room temperature to 250 °C. ( d ) The relative resistance variation Δ R / R 0 of SLG channels as a function of time including recovery step with 100 to 165 °C heating under different NO 2 gas concentration from 40 to 0.5 ppm. Reprinted with permission from Ref. Copyright 2014, John Wiley and Sons. ( e ) Response curves of the sensor to NO 2 of different concentrations. Inset: The sensor response depends linearly on NO 2 concentration. ( f ) Response curves of the sensor to 50 ppm of NO 2 when tested under different bending angles. ( g ) Response curves of the sensor tested before and after bending 1000 and 5000 times (bending angle = 50°). Reprinted with permission from Ref. Copyright 2014, John Wiley and Sons. ( h ) Photograph of microfabricated flexible room temperature ionic liquid (RTIL) based gas sensor (scale bars 1 cm and 2 mm, respectively). ( i ) Current versus time curve at various oxygen concentrations when the potential is held at −1.4 V vs. Au. Nitrogen is the background gas. Oxygen concentration steps up from 0% to 21% and steps down from 21% to 0%. Reprinted with permission from Ref. Copyright 2013, IEEE. ( j ) Schematic illustration of the preparation of the PDA/MoS 2 film and the sensor upon exposure to DMF vapor. ( k ) UV-vis spectra of polydiacetylene (PDA)/MoS 2 composites with an increased ratio of MoS 2 to PDA in the absence and presence of 0.1% DMF vapor. ( l ) UV-vis spectra of PDA/MoS 2 films exposed to N , N -dimethylformamide (DMF) vapor with different concentrations. ( m ) UV-vis spectra of the PDA/MoS 2 film upon exposure to different (5%) vapors, in comparison with 2% DMF vapor. ( n ) Flexible transparent wrist strap with DMF sensing ability. Reprinted with permission from Ref. Copyright 2017, Royal Society of Chemistry.

Article Snippet: In an attempt to solve this problem, Choi et al. reported centimetre-scale transparent graphene sensors for nitrogen dioxide (NO 2 ) gas that had laterally-integrated or vertically-integrated graphene heaters on a polyethersulfone (PES) substrate [ ]. a shows a photograph of a transparent, flexible single-layer graphene (SLG) gas sensor with built-in, bilayer graphene (BLG) heaters. b shows that the temperature of the SLG sensor can reach 165 °C when the BLG heater temperature is 250 °C. c shows the recovery time constant ( τ r ) after using the heaters to apply different temperatures.

Techniques: Concentration Assay, Comparison

Journal: Polymers

Article Title: Smart Sensor Systems for Wearable Electronic Devices

doi: 10.3390/polym9080303

Figure Lengend Snippet: Wearable sensors integrated with resonance antenna. ( a ) Optical image of the graphene-based wireless sensor transferred onto the surface of a tooth (scale bar: 1 cm). ( b ) graphene resistance change versus concentration of H. ( a , b ) Reproduced with permission from Ref. . Copyright 2012, Nature Publishing Group; ( c ) Schematic of the biosensor attached to the skin on the back of a human hand; ( d ) Frequency response of the reflection coefficient of the antenna on the plastic substrates after buffer and Con A treatment. ( c , d ) Reproduced with permission from Ref. . Copyright 2015, John Wiley and Sons; ( e ) Photographs of the RFID tag sensor; ( f ) Change in the reflectance properties. ( e , f ) Reproduced with permission from Ref. Copyright 2016, American Chemical Society. ( g ) Optical photos of wearable gas sensors integrated with resonance antenna transferred onto various substrates (wristwatch, light of bicycle, and a leaf of live plant) (scale bars: 1 cm). ( h ) change in reflection coefficient (S11) of the wireless sensor on the leaf at varied DMMP vapor concentrations (before exposure, 5 ppm of DMMP, 10 ppm of DMMP, and after recovery). ( g , h ) Reproduced with permission from Ref. . Copyright 2016, Royal Society of Chemistry. ( i ) Image of a wireless epidermal sensor attached onto the surface of a balloon to simulate measurement of lymphedema. Scale bar, 1 cm. ( j ) Change in resonance frequencies of strain sensors under the expansion of the balloon. ( i , j ) Reproduced with permission from Ref. . Copyright 2014, John Wiley and Sons. ( k ) Photograph of the sensor transferred onto the contact lens worn by a bovine eyeball. Scale bar, 1 cm. ( l ) Frequency response of the intraocular pressure sensor on the bovine eye from 5 mmHg to 50 mmHg (Inset: the corresponding reflection coefficients of the sensor). ( k , l ) Reproduced with permission from Ref. . Copyright 2017, Nature Publishing Group.

Article Snippet: In an attempt to solve this problem, Choi et al. reported centimetre-scale transparent graphene sensors for nitrogen dioxide (NO 2 ) gas that had laterally-integrated or vertically-integrated graphene heaters on a polyethersulfone (PES) substrate [ ]. a shows a photograph of a transparent, flexible single-layer graphene (SLG) gas sensor with built-in, bilayer graphene (BLG) heaters. b shows that the temperature of the SLG sensor can reach 165 °C when the BLG heater temperature is 250 °C. c shows the recovery time constant ( τ r ) after using the heaters to apply different temperatures.

Techniques: Concentration Assay