Hi. Please help - I'm looking for an OECT sensor similar to the one in this article about measuring the sugar content in xylem - as indicated in this Arduino project. the ability to measure sugar fluctuations in plants over time is of interest to me.
Thanks, clever people
Device fabrication
For the device fabrication a polyethylene naphtalate foil (Teonex Q65HA, 125 µm, Peutz Folien
GMBH) was cut in a circular 4” substrate. The substrate was cleaned with water and acetone,
then vacuum backed for 90 s at 120°C. Metal films of 2nm titanium (Ti) and 50 nm gold (Au)
were evaporated onto the clean surface. Photolithography (Karl Suss MA/BM 6 mask aligner)
and a Shipley 1805 positive resist were used to pattern contacts, wiring, channel and gate. The
substrate was then wet etched in I2/KI solution for Au, and H2O2/NH4Cl/H2O for Ti. The
remaining resist was stripped with acetone. A PEDOT:PSS (Clevios PH1000) mixture with 5%
v/v EG (ethylene glycol) and 1% v/v GOPS (3-Glycidyloxypropyl)trimethoxysilane) and
dodecylbenzenesulfonic acid (50 µl drop per 5 ml) was spin-coated and patterned using a
Shipley 1813 positive resist, then dry etched with CF4/O2 reactive ions, in order to create
channels and gates. The remaining resist was stripped again with acetone. In the end, the
substrate was encapsulated with SU-8 2010 (MicroChem) and openings on the active areas are
defined by wet etching with developer mr-Dev 600 (Microresist Techonology). Chemicals were
used as received from Sigma-Aldrich unless stated otherwise
https://ars.els-cdn.com/content/image/1-s2.0-S2589004220311639-mmc1.pdf, page 7
That probably doesn't help, but does give the clue that these devices aren't very market-ready by the looks of it.
I quickly scanned the methods to see if they say anything about the longevity of these sensors, but it's either not there or I missed it. However, I have a feeling they don't last very long, and given how they're made, I also suspect they're not very easy to store and transport for long periods/distances, causing distribution challenges.
I'm sure if a reliable device were on the market, the authors would have at least considered it; you could always reach out to them and ask this, but I'm afraid we can already guess their answer.
Thank you so much for such a comprehensive response. i have reached out to the authors - hopeful of a response.
Thanks again
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