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. Author manuscript; available in PMC: 2020 Oct 9.
Published in final edited form as: Nano Lett. 2019 Oct 1;19(10):6862–6868. doi: 10.1021/acs.nanolett.9b02070

Figure 5.

Figure 5.

Mechanical and thermal stability of plasmonic microneedle arrays. (a) SER spectra of 4-MBA on a plasmonic microneedle array before puncturing an agar gel skin phantom (black trace), while punctured (blue trace), and after puncturing (red trace). (b) SER spectra of 4-MBA on a plasmonic microneedle array before (black trace) and after (red trace) 10 punches into an agar gel skin phantom. (c) SER spectra of 4-MBA on a plasmonic microneedle array immediately after fabrication (black trace) and on a separate plasmonic microneedle array that was incubated for one month in 1× PBS (green trace). (d) Comparison plot of Acbx/A1076 of MN array with AuNRs functionalized with 4-MBA inserted in human skin versus in DPBS solutions with pH 6.6, 7.1, and 7.6. Each point is an average of seven different microneedle tips, the error bars are the standard deviation at each pH, and the measurements were done by focusing the laser through the polymer and on the tips. The parameters for the SERS data acquisitions were λex = 785 nm, 20× ELWD objective, tacq = 1 min, Pex = 1 mW.