Self-assembled three dimensional network designs for soft electronics

Journal: Nature communications

Author: Kyung-In Jang and John A. Rogers et al.

Affiliation: Daegu Gyeongbuk Institute of Science and Technology, Northwestern University

Publication date: 2017.06.21

Summarized by Jinpyeo Jeung

 

– 3D helical coil (Fig.1)
v. 2D structures limit performance for systems that require low modulus, elastic mechanics in compact designs.
v. 2D precursors spontaneously transform into desired 3D shapes.
v. Compressive forces induced by releasing the prestrain cause the 2D precursor to geometrically transform.
v. Two ends include small discs that form strong covalent siloxane bonds to and substrate.

fig1.png

Fig. 1

 

– Result
v. Enables high levels of strechability and mechanical robustness, without the propensity for localized crack formation or fracture.
v. The elastic stretchability of the 3D helices significantly exceeds that of the 2D serpentines. (Fig.2)
v. Deformations of the 2D serpentine lead to sharp, unavoidable stress concentrations at the arc regions but 3D helices shows uniform stress. (Fig.3)

fig2.png

Fig. 2

fig3.png

Fig. 3

 

– Application
v. Actual appearance. (Fig. 4, Fig. 5)
v. It can be applied to various wireless, skin-compatible electronics. (Fig. 6)

fig4.png

Fig. 4

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Fig. 5

fig6.png

Fig. 6

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Accelerated Wound Healing on Skin by Electrical Stimulation with a Bioelectric Plaster

Journal: Advanced Healthcare Materials

Author: Hiroyuki Kai and Matsuhiko Nishizawa et al.

Affiliation: Tohoku University, Japan

Publication date: 2017.09.20

Summarized by Inyeol Yun

 

– Bioelectric Plaster (Fig. 1)
v. Wound healing on skin involves cell migration and proliferation in response to endogenous electric current.
v. External electrical stimulation is used to promote these biological processes for the treatment of chronic wounds.
v. An enzymatic biofuel cell (EBFC) that generates ionic current along the surface of the skin by enzymatic electrochemical reactions for more than 12h. (Fig. 2)

fig1

Fig. 1

fig2.png

Fig. 2

 

– Materials
v. Cathode : carbon fiber fabric coated with carbon nanotubes, on which reducing enzyme bilirubin oxidase
v. Anode : carbon fiber fabric coated with carbon nanotubes, on which oxidizing enzyme fructose dehydrogenase
v. Hydrogel : citrate buffer solutions with different concentrations of fructose.
v. Stretchable resistor : PEDOT/PU film

 

– Result
v. Time-dependent current changes of the bioelectric plaster with different external resistances and citrate buffer solutions with different concentrations. (Fig. 3)
v. Changes of wound width and height of Group A (gray), Group B (red), and Group C (blue) (Fig. 4)
v. Microscopy images of skin sections at the wound at day 7: a) the boundary between normal tissue and healed tissue, b) the area of normal tissue, c) the area of healed tissue, d) dermis, e) fat tissue (Fig. 5)  Group C > Group A on scar after healing, wound closure speed.

fig3

Fig. 3

fig4

Fig. 4

fig5.png

Fig. 5

 

– Reference
v. https://en.wikipedia.org/wiki/Enzymatic_biofuel_cell (accessed September 26, 2017)

Self-Powered, Paper-Based Electrochemical Devices for Sensitive Point-of-Care Testing

Journal: Advanced Materials Technologies

Publication date: 2017.08.22

Summarized by Inyeol Yun

 

– Self-powered, paper-based electrochemical devices (SPEDs)
v. Structure (Fig. 1)
v. Electrochemical detection (Fig. 2), colorimetric test
v. Triboelectric generator (TEG) (Fig. 3)

fig1

Fig. 1

fig2

Fig. 2

fig3

Fig. 3

 

– Fabrication
v. Biomarker part (Fig. 4)
v. TEG part (Fig. 5)

fig4

Fig. 4

fig5

Fig. 5

 

– Result
v. Electrochemical detection (Fig. 6)
v. TEG (Fig. 7)

fig6

Fig. 6

fig7

Fig. 7

Highly Flexible and Efficient Fabric Based Organic Light-Emitting Devices for Clothing-Shaped Wearable Displays

Journal: Scientific Reports

Publication date: 2017.07.25

Summarized by Seongmin Park

 

– Methods to achieve actual clothing-shaped information displays

  1. Attaching a display panel onto a piece of clothing → Flexibility decreases
  2. Fabricating of light emitting fiber → Low emission performance
  3. Fabricating an information display onto a fabric → Best choice

– Novel Concept

v. Spin coating of the silane-based film on fabric (Fig. 1, 2)

fig1

Fig. 1

fig2

Fig. 2

– Structure

  1. Base Structure (Fig.3)

fig3

Fig. 3

     2. Endurance vs. Number of dyads (Fig. 4, 5)

fig4

Fig. 4

fig5

Fig. 5

     3. Optimized Structure (Fig. 6)

fig6

Fig. 6

     4. Good Endurance

fig7

Fig. 7

 

– Results

  1. Similar performance (Fig. 8)

fig8

Fig. 8

     2. Light emitting performances vs. bending radius (Fig. 9)

fig9

Fig. 9

     3. Comparison between OLEDs on fabric and OLEDs on PET (Fig. 10)

fig10

Fig. 10

     4. Cyclic bending with bending radius of 1 cm (Fig. 11)

fig11

Fig. 11

 

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

 

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