Fig. 1: MNP fabrication using the MVP.

a, Modular inks containing mRNA, lipids and polymer can be customized for microneedle vaccine printing. b,c, The MVP (b) can be distributed to remote areas to provide local manufacturing capability (c) of thermostable MNPs. d, After automated dispensing, vacuum is applied through PDMS to load the polymer–vaccine solution into the microneedle mold. Molds are then transferred to a drying station for accelerated drying. e, The time needed to load the polymer–vaccine solution into the PDMS mold was measured for various design and process parameters. Unpaired, two-tailed t-tests were used for all comparisons, except for polymer type, where an ordinary one-way ANOVA was used (n = 3 independent samples). f, Drying rate for different drying strategies. ANCOVA was used to compare drying rate estimates, which were derived from a linear regression of drying rate data (n = 3 independent samples). g, Total drop area (n = 3 independent samples) and patch coverage (n = 100 independent samples) are a function of polymer solution used for dispensing. h, Imaging of MNPs fabricated with the device: MNP on acrylic solid backing (top left), SEM image of MNPs with conical (top right) and pyramid (bottom left) geometries and a single pyramid MNP (bottom right). i, Images of tip-loaded MNPs (outlined in white) co-dispensed with the device using red (top) or blue (bottom) dye as model cargo. j, MNP production throughput. k, MNP throughput as a function of drying time and printing tray length. Data represent the mean ± s.d (e,g) or mean ± 95% confidence interval (f). P values are represented by: *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001. NS, not significant.