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Carrier-based interactive powder mixtures are a cornerstone of drug delivery by inhalation, yet optimization is hampered by the complex interplay of various carrier particle properties including their geometry. 10 August 2026 Inhalation Geometry matters: Recent advances, strategies and emerging technologies in engineering carrier particles for lung delivery Utilizing 3D-printed particles, numeric models and Bayesian optimization to elucidate the influence of carrier geometry in adhesive mixtures Dr. rer. nat. Melvin Wostry and Prof. Dr. rer. nat. Regina Scherließ Kiel University Abstract Carrier-based interactive powder mixtures are a cor- nerstone of drug delivery by inhalation, yet optimiza- tion is hampered by the complex interplay of various carrier particle properties including their geometry. Conventional approaches for carrier particle manu- facture such as milling, sieving or spray drying can modify multiple attributes simultaneously, making it challenging to assess the effect of particle geom- etry. To address this, two innovative strategies were applied and are presented in this article: in-silico modeling and the use of 3D-printed carrier parti- cles. Discrete element method simulations allowed the systematic study of virtual drug particle attach- ment and detachment from carriers of defined geometries. Complementarily, recent advances in two-photon-polymerization enabled the fabrication of millions of uniform, geometry-controlled particles for aerodynamic testing. Four geometries—Sphere, Soccerball, Rollingknot and Pharmacone—were investigated, with the Pharmacone exhibiting supe- rior performance, achieving a fine particle fraction exceeding 16% of the emitted dose, largely attributed to its surface spikes that enhance detachment via chaotic movement and collisions. Building on this, a parametric Satellite geometry was created and opti- mized through a fully automated in-silico workflow integrating Bayesian optimization, identifying design rules for spike dimensions and surface features. ese studies demonstrate that carrier geometry is a criti- cal determinant of drug detachment and aerosoliza- tion efficiency. Together, advanced 3D printing and in- silico optimization can provide a powerful frame- work for designing carrier particles with tailored geometries, offering new opportunities to enhance the performance of dry powder inhalers. Introduction In the field of inhaled drug delivery, carrier-based interactive powder mixtures are an established dry powder formulation strategy [1]. e combination of coarse carrier particles with micronized drug can improve powder metering for highly potent active pharmaceutical ingredients (APIs) and have a ben- eficial influence on aerosolization of the API during inhalation. Carrier-based dry powder inhalers (DPIs) have seen various approaches for product improve- ment over the last decades [1]. When considering the API, micronization via jet milling is typically used to achieve sufficiently small particles for lung delivery. However, this approach can lead to increased cohe- siveness, which in turn reinforces the use of interac- tive powder mixtures to reduce API-to-API particle interactions. Typically, α-lactose monohydrate is used as carrier particle in interactive blends for inha- lation. While a typical lactose crystal resembles a