A variety of hollow microneedle (HMN) designs has emerged for minimally invasive therapies and monitoring systems. In this study, a design change limiting the indentation depth of the (3D) printed custom microneedle assembly (circular array of five conical frusta with and without a stopper, aspect ratio = 1.875) fabricated using stereolithography has been experimentally validated and modeled in silico. The micro-indentation profiles generated in confined compression on 1 mm ± 0.073 mm alginate films enabled the generation of a Prony series, where displacement ranged from 100 to 250 µm. These constants were used as intrinsic properties simulating experimental ramp/release profiles. Puncture occurred on two distinct hydrogel formulations at the design depth of 150 µm and indentation rate of 0.1 mm/s characterized by a peak force of 3.5 N (H = 31 kPa) and 8.3 N (H = 36.5 kPa), respectively. Experimental and theoretical alignments for peak force trends were obtained when the printing resolution was simulated. Higher puncture force and uniformity inferred by the stopper was confirmed via microscopy and profilometry. Meanwhile, poroviscoelasticity characterization is required to distinguish mass loss vs. redistribution post-indentation through pycnometry. Results from this paper highlight the feasibility of insertion-depth control within the epidermis thickness for the first time in solid HMN literature.

Burn injuries are functionally limiting, and premorbid mobility impairments may further complicate recovery. Premorbid mobility impairments are associated with worse outcomes in other populations; however, their role in burn recovery remains unclear. This retrospective cohort study included adult burn survivors injured from 2014 to 2025 extracted from the Burn Model System National Burn Database. Premorbid mobility impairment was defined as self-reported preburn physical problems or impairments affecting mobility (difficulty moving the arms, legs, or body). Outcomes included length of stay, discharge disposition, and PROMIS Global Mental Health scores at 6- and 12-month follow-ups postinjury. All regression models were adjusted for age, TBSA, and inhalation injury. The model for Global Mental Health scores additionally adjusted for discharge location, Global Physical Health, preinjury Global Mental Health, and follow-up time. A total of 1372 adult burn survivors were included, with a mean age of 46.2 years. Premorbid mobility impairment was associated with longer hospital stay (incidence rate ratio 1.15; 95% CI, 1.04-1.27; P = .006) and discharge to a shelter (odds ratio 1.75; 95% CI, 1.41-2.19; P < .001). There was also a trend toward lower PROMIS Mental Health scores among survivors with premorbid mobility impairments (β = −1.92, P = .091). Premorbid mobility impairment is associated with poorer burn outcomes, including longer hospital stay and discharge to unstable settings such as shelters, and may also be linked to poorer mental health outcomes. It remains unclear whether shelter discharge reflects premorbid housing instability or a new postburn disposition.

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