#  Wetting in color (W-Ink) 

 



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Colorimetric litmus tests such as pH paper have enjoyed wide commercial success due to their inexpensive production and exceptional ease of use. Many such techniques operate based on a chemical tag whose optical absorption or fluorescence spectrum changes in response to a specific analyte. Specificity is an advantage in this case, but limits the variety of substances for which such a sensor can be used. On the other hand, the use of structural color – derived not from molecular absorption but from coherent scattering from wavelength-scale roughness – has no inherent specific chemical requirements (e.g. any material with periodic roughness displays iridescence). Thus, tunable structural color carries the potential for broad applicability in colorimetric sensing.   
  
We developed a technique for patterning multiple chemical functionalities throughout the inner surfaces of a highly ordered 3D photonic crystal, generating complex wettability patterns. When immersed in a liquid, the pores are selectively infiltrated in a unique spatial pattern. This creates an optical fingerprint of that liquid through the color contrast between wetted and non-wetted regions. Using this platform, we have illustrated multilevel encryption, with selective decoding by specific liquids. A remarkable selectivity of wetting is observed over a very broad range of fluid surface tensions. These properties, combined with the easily detectable optical response, allow us to also exploit this system as a colorimetric indicator for liquids based on wettability.



 

##  Publications 

 



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### 2013

Burgess I, Loncar M, Aizenberg J. [Structural Colour in Colourimetric Sensors and Indicators](/publications/structural-colour-colourimetric-sensors-and-indicators). J. Mater. Chem. C. 2013;1(38):6075–6086. doi:10.1039/C3TC30919C



 

 

Burgess I, Loncar M, Aizenberg J. [Structural Colour in Colourimetric Sensors and Indicators](/publications/structural-colour-colourimetric-sensors-and-indicators). J. Mater. Chem. C. 2013;1(38):6075–6086. doi:10.1039/C3TC30919C



 

 

 

- add\_circle\_outline do\_not\_disturb\_on Abstract
- [ descriptionPublisher's Version](http://pubs.rsc.org/en/content/articlelanding/2013/tc/c3tc30919c#!divAbstract)
 
 Colourimetric sensors and indicators are widely used because of their low cost and simplicity. A significant challenge associated with the design of this type of device is that the sensing mechanism must be simultaneously optimised for the sensitivity of... 

 

 

- [ descriptionPublisher's Version](http://pubs.rsc.org/en/content/articlelanding/2013/tc/c3tc30919c#!divAbstract)
 
 

 



### 2012

Burgess I, Koay N, Raymond K, Kolle M, Loncar M, Aizenberg J. [Wetting in Color: Colorimetric Differentiation of Organic Liquids with High Selectivity](/publications/wetting-color-colorimetric-differentiation-organic-liquids-high-selectivity). ACS Nano. 2012;6(12):1427–1437. doi:10.1021/nn204220c



 

 

Burgess I, Koay N, Raymond K, Kolle M, Loncar M, Aizenberg J. [Wetting in Color: Colorimetric Differentiation of Organic Liquids with High Selectivity](/publications/wetting-color-colorimetric-differentiation-organic-liquids-high-selectivity). ACS Nano. 2012;6(12):1427–1437. doi:10.1021/nn204220c



 

 

 

- [ picture\_as\_pdfWICK\_ACS\_Nano.pdf](/sites/g/files/omnuum6296/files/WICK_ACS_Nano_0.pdf)
 
- [ picture\_as\_pdfWICK\_ACS\_Nano.pdf](/sites/g/files/omnuum6296/files/WICK_ACS_Nano_0.pdf)
 
 

Raymond K, Burgess I, Kinney M, Loncar M, Aizenberg J. [Combinatorial Wetting in Colour: An Optofluidic Nose](/publications/combinatorial-wetting-colour-optofluidic-nose). Lab on a Chip. 2012;12:3666–3669. doi:10.1039/C2LC40489C



 

 

Raymond K, Burgess I, Kinney M, Loncar M, Aizenberg J. [Combinatorial Wetting in Colour: An Optofluidic Nose](/publications/combinatorial-wetting-colour-optofluidic-nose). Lab on a Chip. 2012;12:3666–3669. doi:10.1039/C2LC40489C



 

 

 

- [ picture\_as\_pdfLabChip2012.Raymond.pdf](/sites/g/files/omnuum6296/files/LabChip2012.Raymond_0.pdf)
 
- [ picture\_as\_pdfLabChip2012.Raymond.pdf](/sites/g/files/omnuum6296/files/LabChip2012.Raymond_0.pdf)
 
 

Wang W, Burgess I, Hatton B, Alvarenga J, Aizenberg J. [Secrets revealed - Spatially selective wetting of plasma-patterned periodic mesoporous organosilica](/publications/secrets-revealed-spatially-selective-wetting-plasma-patterned-periodic-mesoporous). Can. J. Chem. 2012;90(12):1063–1068. doi:10.1139/v2012-092



 

 

Wang W, Burgess I, Hatton B, Alvarenga J, Aizenberg J. [Secrets revealed - Spatially selective wetting of plasma-patterned periodic mesoporous organosilica](/publications/secrets-revealed-spatially-selective-wetting-plasma-patterned-periodic-mesoporous). Can. J. Chem. 2012;90(12):1063–1068. doi:10.1139/v2012-092



 

 

 

- [ picture\_as\_pdfCanJChem\_2012\_patterning%...](/sites/g/files/omnuum6296/files/CanJChem_2012_patterning%2520PMO%2520through%2520plasma_Wendong_0.pdf)
 
- [ picture\_as\_pdfCanJChem\_2012\_patterning%...](/sites/g/files/omnuum6296/files/CanJChem_2012_patterning%2520PMO%2520through%2520plasma_Wendong_0.pdf)
 
 

 



### 2011

Burgess I, Mishchenko L, Hatton B, Kolle M, Loncar M, Aizenberg J. [Encoding complex wettability patterns in chemically functionalized 3D photonic crystals](/publications/encoding-complex-wettability-patterns-chemically-functionalized-3d-photonic-crystals). J. Am. Chem. Soc. 2011;133(32):12430–12432. doi:10.1021/ja2053013



 

 

Burgess I, Mishchenko L, Hatton B, Kolle M, Loncar M, Aizenberg J. [Encoding complex wettability patterns in chemically functionalized 3D photonic crystals](/publications/encoding-complex-wettability-patterns-chemically-functionalized-3d-photonic-crystals). J. Am. Chem. Soc. 2011;133(32):12430–12432. doi:10.1021/ja2053013



 

 

 

- [ picture\_as\_pdfJACS\_W-Ink\_2011.pdf](/sites/g/files/omnuum6296/files/JACS_W-Ink_2011_0.pdf)
 
- [ picture\_as\_pdfJACS\_W-Ink\_2011.pdf](/sites/g/files/omnuum6296/files/JACS_W-Ink_2011_0.pdf)
 
 

 



 

 

 

 

 

 

##  Media Gallery 

 



  [### wink.1\_04.jpg

 ](/resource/wink104jpg) 

 

 

   ![Wetting in color (W-Ink) 2](/sites/g/files/omnuum6296/files/styles/hwp_16_9__480x270/public/aizenberg/files/wink.1_04.jpg?itok=Nl-YL9QE) 

 



 

 

   [### w-ink\_press\_04.png

 ](/resource/w-inkpress04png) 

 

 

   ![Wetting in color (W-Ink) 1](/sites/g/files/omnuum6296/files/styles/hwp_16_9__480x270/public/aizenberg/files/w-ink_press_04.png?itok=8hjIq8_o) 

 



 

 

  

 

 

 

 

##  Media Coverage 

[Materials inspired by nature](http://physicsworld.com/cws/article/multimedia/2014/jun/11/materials-inspired-by-nature), Physics World, June 11, 2014.

["Watermark Ink" device (W-INK) wins R&D 100 Award](http://wyss.harvard.edu/viewpressrelease/118/watermark-ink-device-wink-wins-rd-100-award) Harvard press release, July 8, 2013.

[Colourimetry: Combinatorial Wetting](http://www.nature.com/nphoton/journal/v6/n8/full/nphoton.2012.198.html?WT.ec_id=NPHOTON-201208), Nature Photonics, July 31, 2012.

[Nanocrystal Liquid Identification](http://www.cosmeticsandtoiletries.com/research/techtransfer/131161428.html), Cosmetics & Toiletries, October 5, 2011.

[Surface tension decoded](http://www.rsc.org/chemistryworld/Issues/2011/September/NewsInBrief.asp), Chemistry World, September 2011.

[Channeled chips can spot substances](http://www.scientificamerican.com/podcast/episode.cfm?id=channeled-chips-can-spot-substances-11-08-11), Scientific American, August 11, 2011.

[Devices Reveal Hidden Messages](http://cen.acs.org/articles/89/i33/Devices-Reveal-Hidden-Messages.html), Chemical & Engineering News, August 15, 2011.   
[](http://www.seas.harvard.edu/news-events/press-releases/watermark-ink)

["Watermark Ink" device identifies unknown liquids instantly](http://www.seas.harvard.edu/news-events/press-releases/watermark-ink), Harvard press release, August 3, 2011.

[Inverse opal technology could help identify chemical spills](http://www.theengineer.co.uk/electronics/news/inverse-opal-technology-could-help-identify-chemical-spills/1009572.article), The Engineer, August 4, 2011.

["Watermark Ink" device identifies unknown liquids instantly](http://www.materialstoday.com/view/20007/watermark-ink-device-identifies-unknown-liquids-instantly/), Materials Today, August 10, 2011.

["Watermark Ink" chip can instantly identify liquids](http://www.gizmag.com/watermark-ink-chips-identify-liquids/19439/), Gizmag, August 4, 2011.