I'm currently trying to use the method outlined in this paper to add a micrometer scale pattern over a nanopillar array, the final application being tissue engineering.
My substrates are injection moulded polycarbonate pieces, so the use of PAA for patterning is attractive as standard photolithographic processes aren't compatible with the material. Also, being able to essentially do a lift off in water is ideal as I'll be patterning biomolecules which are sensitive to solvents.
My progress so far:
i) I've modified the pH of a solution of 25% w/v PAA from ~pH2 to ~pH 7 using a saturated solution of NaOH, as described in the paper. How important is the accuracy here? is, for example, 7.1 ok - or should I get as close to 7.5 as possible.
ii) I spin coat this solution at 6k rpm for 30s - giving a 1.8um film. This thickness is necessary to completely cover my existing structures.
iii) Immersing these samples in a 1M solution of CaCl2 results in their turning opaque, as though something is precipitating. They also lose adhesion to silicon substrates, but that is to be expected. They are not water soluble which is good, but their roughness is a problem.
An image of my samples thus far:
http://imgur.com/3GbqwjO
Could the authors offer any advice or tips on working with PAA films? Any help would be much appreciated.
Article Patterning micron-sized features in a cross-linked poly(acry...
We have done that the impact of the treatment was evaluated and certified by qualified psychologists using the following instruments: IQCODE, ASAS-Cog , CASI , CDR, NPI, PANAS , ISI, PSQI to self-assess / report, plus using the non-invasive AURA VIDEO STATION 7 SYSTEM (Power AVS 7) to monitor and assess the moods , sleep and the physical conditions of the elderly subjects at three-month interval, lasting for six months.
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