Drawing sensors with a simple ball point pen powered by nanotechnology

What do you normally do once your ball point pen runs out?  Most people would throw them away, but now engineers at the University of California, San Diego have created a new type of refill ink for your pen that isn’t harmful allowing you to draw sensors anywhere including on your skin and on your plants!

The research published in the paper “Biocompatible Enzymatic Roller Pens for Direct Writing of Biocatalytic Materials: “Do-it-Yourself” Electrochemical Biosensors” described how the inks could function as electrodes for sensors as well as keep their properties over long periods of storage time.

Created using biocompatible polyethylene glycol to act as a binder and graphite powder to make the ink conductive, the researchers also added chitosan to help the ink stick and xylitol to stabalise the enzymes specifically added for each sensor function.

The pens open up new scope for people to draw sensors that detect pollutants and potentially harmful chemicals sensors in any location, and have proved this concept by drawing a sensor on a leaf with an ink loaded with enzymes that react with phenol (an industrial chemical) which was then connected to a pollution detector.

The next step for the sensor is to connect them wirelessly to monitoring devices and investigating how the sensors perform in difficult conditions, including extreme temperatures, varying humidity and extended exposure to sunlight.

To hear more about this technology and how it may be used, listen to my Radio Live interview here.

 

 

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A Jacket that powers your devices using nanotechnology

Jacket powered by your own movements, showing integrated LCD screen, LED lights, power controller and remote control thanks to its nanotechnology coated fabric fibres.  Image Source)

Jacket powered by your own movements, showing integrated LCD screen, LED lights, power controller and remote control thanks to its nanotechnology coated fabric fibres. (Image Source)

What if the jacket that you were wearing to keep you warm, also had the capability of generating electricity from your tiniest movements such as your heartbeat or blood flow to the larger movements from you walking around to use for powering integrated electronics or sensors.

Well researchers at Sungkyunkwan University and the University of Wollongong are one step closer as shown in their paper “Nanopatterned textile based wearable triboelectric nanogenerator” published in ACS Nano.

The triboelectric effect occurs when certain materials become electrically charged when they are rubbed against a different material.  Rubbing a balloon on your hair builds up triboelectricity and most static electricity shocks that you get from your winter clothing are triboelectric.  The rubbing action causes one of the materials to transfer electrons to the other, and if the surface area of the rubbing surfaces is large enough, results in a massive excess of electrons which can then be used to power devices.  Nanofibres have a large surface area to volume ratio meaning that they are able to create very large rubbing surfaces in a very small space, thus increasing the number of electrons transferred.

The fibre in the jacket is coated first with silver, then ZnO nanorods are grown on top, with a final PDMA dip coating to increase abrasion resistance for a longer lasting jacket. (Image  adapted from source)

The triboelectric effect is not new and previous attempts have been made to try and create clothing that charges devices, however their main drawback has been durability.  Clothing typically has to withstand abrasion and wear forces without being rubbed off.  This study solved that issue by using the polymer PDMS as a fibre coating on top of the ZnO nanorods which were laid onto the silver coated fabric resulting in no loss of voltage after 12,000 cycles.

Although still a prototype device, the study moves researchers closer to solving one of the biggest issues with wearable tech fibres of how to increase the usable lifetime of the fabric.

 

Chameleons colour changing secret discovered to be nanotechnology!

Chameleons are one of natures most incredible creatures with their ability to quickly change colour for social reasons or personal protection.

They have populated myths and legends and were even described by Aristotle due to their unusual features including their independently moveable eyes, long projectile tongue and zygodactylous (two toes forward, two behind) feet.

Previously it was thought that chameleons changed colour through pigments in their skin, but this week research published in Nature communications revealed its actually through nano-photonic crystals found in a layer of cells called iridophores which lie below the chameleons pigment cells.

So chameleons have been secretly using nanotechnology all along!   I knew I liked them for a reason!

Transmission Electron Microscope images of the lattice of guanine nanocrystals in iridophores from the same chameleon in a relaxed and excited state. The relaxed state has a higher crystal density resulting in reflection of blue light wavelengths, the less dense excited state results in red and yellow light wavelength reflection. Adapted image source

Transmission Electron Microscope images of the lattice of guanine nanocrystals in iridophores from the same chameleon in a relaxed and excited state. The relaxed state has a higher crystal density resulting in reflection of blue light wavelengths, the less dense excited state results in red and yellow light wavelength reflection. Adapted image source

Iridophores are not new and they are found in other reptiles and amphibians resulting in the blue and green colours that are not often found in vertebrates, but the difference is that chameleons have lattices of these nanocrystals which they can tune to alter the way that the light is reflected.

If the chameleon is calm, the crystals are organised into a dense network which reflect the blue wavelengths of incoming light.

If the chameleon is excited, it loosens the dense lattice and this allows the reflection of yellow and red wavelengths.

The study also discovered that chameleons have a deeper layer of iridophore cells which contain larger and less ordered crystals which reflect infrared wavelengths from sunlight.  This  protects the chameleon from the heat of the strong sun by arming them with a natural heat shield.

Scientists still don’t understand the mechanism behind how the chameleon fine tunes the nanocrystals but this new research can help with alternative ways to protect man made object from high heat sources.

To hear more on my views on this new finding, click here to listen to my Radio Live chat with Mark Sainsbury