GCSE D&T Help Site

WHAT IS A SMART MATERIAL?

  A smart material or ink, is one that reacts to its surroundings, for example by changing colour.

THERMOCHROMIC INKS

  · These react to HEAT.

· There are two layers of ink on top of each other. When heat is applied, the top thermochromic layer goes CLEAR revealing the colour underneath.

· They are often used for items  such as

· battery testers, forehead

· thermometers and novelty items and packaging

· It’s also been used on DVDs that smell once played (as they get hot)


  PHOTOCHROMIC INKS

· These react to LIGHT.

· There are two layers of ink on top of each other. When light is applied, the top photochromic layer goes CLEAR revealing the colour underneath.

· They are most commonly seen on screen printed textiles, but there use is limited as the ink only withstands

·approximately 20 washes.

· They are also used in light sensitive sunglasses.


HYDROCHROMIC INKS

  · These react to MOISTURE.

· There are two layers of ink on top of each other. When moisture/water is applied, the top hydrochromic layer goes CLEAR revealing the colour underneath.

·  Often used for applications where the product will get wet, eg umbrellas


  MICRO ENCAPSULATION

  · This is the principle behind ‘scratch & sniff’

· Tiny spheres (balls) contain the smell (eg perfume) and when you rub the printed ink these spheres burst, releasing the smell.

· It is often used for perfume advertisements and promotional stickers