Improvements in sensitivity by roughly an order of magnitude can easily be envisioned by increasing the molecular weight between crosslinks in the low index layers, which would lead to a more pronounced change in the degree of swelling after irradiation — since each net dislinking event would correspond to a proportionally larger change in crosslink density — and therefore a more pronounced colorimetric response at lower doses. Further improvements should be possible through optimization of the copolymer chemistry. For example, copolymerization with methacrylic acid is known to
increase the sensitivity of PMMA-based photoresists substantially [23], and a similar strategy could be employed here to improve the sensitivity of preferentially dislinking sensors to lower doses of radiation, i.e., by increasing the yield of dislinking reactions relative to crosslinking or other chemical reactions that do not affect backbone bonds.