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Researach from January 2017 - June 2017 (EPSRC grant). Joint research with Chester and Cambridge Universities.
1. Sample conveyor for a teraherz spectrometer
Zeng, Y., Edwards, M., Stevens, R., Bowen, J., Donnan, R. S., & Yang, B. (2017). Terahertz characterisation of UV offset lithographically printed electronic-ink. Organic Electronics.
Version 1
Terahertz (THz) spectroscopy is a remote method that spans between the mid-infrared and millimeter microwave region. and can be used to to measure the quality of ink-jet printed electronics on paper. However, terahertz spectroscopy can take several minutes to sample a region of printed ink making an automayed conveyor system a viable system to measure large areas.
Towards this goal I developed several conveyors prototype built from cheap materials, such as discarded CD-ROMs, and which would allowed printed ink samples to be moved in 1D and 2D pathsways through the Teraherz beam.
I built version 1 by scavenging my broken MakerBot 3D printer. It's casing and servos became useful to build this prototype. The actual conveyor is situated inside the box and is composed of an aluminum plate and two rollers, one of which is motorized for pulling the printed ink paper. Servos attached to a 2D gantry moving the conveyor (part made from aluminum and rollers) in 2D for higher resolution analysis of the ink regions.
Version 2
I built version from old CD-ROM components but is used to sample small regions of printed ink electronics as it has limited 2D motion (see video). An ink sample is attached onto the plate and moved in increments of approximately 2mm horizontally and vertically. The conveyor is programmed to mode the sample in a meandering line through the teraherz beam.
Version 3
Version 3, a 1D conveyor, was smaller than version 1 and could also be easily fitted within the teraherz rig. it was built using 3mm acrylic and my 40W laser cutter. It has two rollers as version 1 with one powered by a 12V servo. Guides housed along the sides help the paper travel in a straight line. Friction at the turning points (90 degree regions of direction change) was reduced using smooth aluminum bars.
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As the paper travelled in increments of 2mm the teraherz beam would scan a 1D string of the printed electronics and provide a simple characterization tool for ink print quality.
Version 4
Version 4 was built in order to sample the printed paper in a different teraherz rig at TeraView, Cambridge. I needed to build a flat conveyor system and used a single high friction rubber roller (beneath the paper in the image) to pull the paper electronics through the teraherz beam.
2. Design of a vibrating sample rig for the teraherz spectrometer
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Changing the path length of the teraherz beam towards the sample in real time could reduce the total loss of the sample peak signal. we wanted to test this idea by being able to vibrate the sample in the teraherz beam and see if we could isolate the sample peak.
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I designed three vibration rig prototypes that work using; (i) a cam where the rotational frequency is converted into linear vibration; (ii) and (iii) used a solonoid whose frequency is adjusted with current. The problem with this method was that the frequency amplitude of motion is not consistent.
3. Teraherz Visualization of nano-materials
Zeng, Y., Edwards, M., Stevens, R., Bowen, J., Donnan, R. S., & Yang, B. (2017). Terahertz characterisation of UV offset lithographically printed electronic-ink. Organic Electronics.
An ink printed electronic sample was placed onto the version 2 conveyor and programmed to moved in the teraherz beam in increments of 2mm horizontally and vertically. Visualizing the ink lines was possible by rasterizing the resulting table of teraherz reflection values.
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This was a positive result showing that the design of the conveyor was good for sampling small regions at high resolution.
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