Fully Screen-Printed, Large-Area, and Flexible Active-Matrix Electrochromic Displays Using Carbon Nanotube Thin-Film Transistors

Journal: American Chemical Society NANO

Publication date: 2016.10.17

Summarized by Sejin Kim

 

– The fabrication process of the fully screen-printed flexible active-matrix electrochromic display using SWCNT(single-walled CNT) TFTs.

fig1.png

Fig. 1

fig2.png

Fig. 2

v. Figure (a)

  1. High-purity semiconducting SWCNTs were incubated on a 5 × cm2 PET substrate.
  2. The printing of silver source and drain electrodes and data lines.
  3. The printing of a BTO layer (barium titanate/gate dielectric) on the channel region of each TFT.

v. Figure (b)

  1. Printed BTO layer was used as a hard mask for etching to remove the unwanted SWCNTs outside the TFT region.
  2. Then another BTO layer was printed as a passivation layer to protect the data lines and the ground lines.

v. Figure (c)-(e)

  1.  Scan lines, ground lines, PEDOT:PSS layer, and electrolyte were screen-printed sequentially+.

 

– The fully screen-printed flexible electrochromic cells.

Fig. 3

v. The switching time of this electrochromic cells : 2−5 s

v. The printed EC cell operates reliably under bending.

v. Negligible degradation of the electrical performance after 7 days in air.

 

– The control of coloration and retention behavior by changing VScan and VData

Fig. 4

v. Vscan = -10V [TFT on], VData = 4V: the oxidation of PEDOT:PSS-> [transparent state]

v. Vscan = 10V [TFT off], VData = 4V: the pixel color is retained.

v. Vscan = -10V [TFT on], VData = -4V à the reduction of PEDOT:PSS -> [dark-blue state]

v. Vscan = 10V [TFT off], VData = – 4V: the pixel color is retained.

fig5.png

Fig. 5

 

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Graphene Electronic Tattoo Sensor

Journal: ACSNANO

Publication date: 2017.07.18

Summarized by Inyeol Yun

 

– Graphene electronic tattoo (Fig. 1)
v. serpentine design
v. cost- and time-effective fabrication
v. thickness : 463 ± 30 nm  laminated by Van der Waals forces
v. optical transparency : ~85%
v. stretchability : >40%
v. ECG, EMG, EEG, skin hydration and skin temperature sensing

fig1

Fig. 1

– Fabrication (Fig. 2)
v. Graphene : CVD Growth
v. PMMA-assisted transfer

fig2.png

Fig. 2

– Device characteristics
v. Thickness, Transparency, Stretchability (Fig. 3)

fig3.png

Fig. 3

– Result

v. ECG, EMG, EEG (Fig. 4)

 v. Skin hydration (skin impedance) and skin temperature sensing (Fig. 5)

fig4.png

Fig. 4

fig5

Fig. 5

 

Fully Printable, Strain-engineered Electronic Wrap for Customizable Soft Electronics

Journal: Scientific Reports

Publication date: 2017. 03. 24

Summarized by Inyeol Yun

 

– Concept

v. PDMS-PRI-PDMS Structure (Fig. 1)

v. Devices (LEDs, IC Chips) are mounted on PRI (Printed Rigid Island).

v. Concept from stretchable beat network (Fig. 2)

v. Device (bead) is stable because stress is concentrated on PDMS (spring) when mechanical deformation is applied to the wrap. (Fig. 3)

v. Printed silver wire was encapsulated by PDMS -> prevent silver wire deformation

fig1

Fig. 1

fig2

Fig. 2

fig3

Fig. 3

 

– Fabrication

v. Fabrication process of the PRI-embedded soft wrap (Fig. 4)

v. Devices were bonded with inkjet-printed Ag pads via Ag epoxy. (Fig. 5)

fig4.png

Fig. 4

fig5

Fig. 5

Stretchable Active Matrix Inorganic LED Display Enabled by Overlay-Aligned Roll-Transfer Printing

Journal: Advanced Functional Material

Publication date: 2017. 03

Summarized by Sejin Kim

 

– Roll-Transfer of Inorganic Components on Arbitrary Substrates

 

v. The three steps of transfer process

  1. Transfer of the Si-TFTs from the bulk SOI wafer to a carrying substrate
  2. Transfer of the LEDs from an AlInGaP wafer to a carrying substrate
  3. Integration of the display, followed by transfer from the carrying substrate to rubber or plastic substrate

fig1.png

Fig. 1

 

– TFT Fabrication for Printing Process

v. Picking step

fig5.png

Fig. 2

fig6.png

Fig. 3

  1. Conventional TFT fabrication
  2. Etching BOX with the ribbon pattern of PR mask
  3. Etching of the exposed bulk Si by inductively coupled plasma RIE

v. Placing step

  1. Printing of TFT onto the prepared PMMA/glass substrate

fig7.png

Fig.4

 

– Integration of Si-TFT and μ-LED on a Temporary Substrate Using Roll Transfer

fig9.png

Fig. 5

  1. Undercutting of μ-LED by selectively eliminating the sacrificial layer (AlAs)
  2. Picking of the μ-LED with automated roll-to-plate printing machine with two mounted microscopes

fig6

Fig. 6

 

– Transfer Printing on Elastomer Substrate

Fig. 7

  1. Reactive-ion etching of the epoxy layers and NOA (with O2 for 40 min)
  2. The exposed PMMA sacrificial layer was dissolved
  3. Transfer of the device from glass to PDMS substrate (the PDMS substrate was baked at 70 °C for making a strong bond between the device and the PDMS substrate)

 

– Stretchable LED Display with Si Backplane TFTs

Fig. 8

v. The elastic interconnects are composed of polymeric encapsulated metals with a sandwiched structure and are located in the neutral plane

 

fig16.png

Fig. 9

v. Most of the strain occurs on the serpentine-shaped bridge region; the strain on the island region is negligible.

Top Down Fabrication Meets Bottom-up Synthesis for Nanoelectronic Barcoding of Micro Particles

Journal: Lab on a chip

Publication date: 2017. 06

Summarized by Jinpyeo Jeung

 

– Nanoelectrically barcoded micro particles (Fig. 1)

v. Could be used in biomarker based diagnostics

v. Allows miniaturization of the readout instrument thus suitable for wearable device

v. Structure similar to Janus microparticles (JPs)

v. Polystyrene bead (3μm diameter), gold (20nm), Aluminium oxide (5nm, 20nm)

v. Due to difference in capacitance of bead, shows different frequency response (Fig. 2)

fig1.png

Fig. 1

fig2.png

Fig. 2

 

– Fabrication (Fig. 3)

v. Polystyrene microsphere self assembled onto a glass substrate using drop-casting

v. Wafer heated to evaporate liquid

v. Using electron beam evaporation, deposited gold layer

v. Using ALD, deposited an insulative layer

v. Particles lifted off from the film using ultrasonification

fig3.png

Fig. 3

 

– Result (Fig. 4)

v. 4 different bead could be distinguished by frequency response data

v. successful barcoding of micro particles

fig4.png

Fig. 4

 

Batch Fabrication of Customizable Silicone-Textile Composite Capacitive Strain Sensor for Human Motion Tracking

Journal: Advanced Materials Technology

Publication date: 2017

Summarized by Inyeol Yun

 

– Highly stretchable textile-silicone capacitive sensor (Fig. 1)

v. Conductive knit fabric as electrode

v. Silicone elastomer(Ecoflex0030) as dielectric

v. Sensing principle (Fig. 2)

fig1

Fig. 1

fig2

Fig. 2

 

– Fabrication

v. Supporting Information : admt201700136-sup-0002-S2.mp4 http://onlinelibrary.wiley.com/doi/10.1002/admt.201700136/full

 

– Result

v. Capacitance output of the fingers during hand motion (Fig. 3)

fig3

Fig. 3