Driven by ever shorter cycles of innovation, organizations and individuals nowadays have to acquire, understand and apply new knowledge in shorter periods of time . Much of this rapid learning appears to be achieved by workers learning on the job and from colleagues - informal learning rather than learning from traditional, curriculum-based training . Mobile technology could potentially provide support to this informal learning as it can provide scalable and flexible learning tools that can be used at any time across a variety of locations: at home, on different work sites, during travel . However, designing learning technology that can support such unstructured, creative and expertise-driven informal learning is challenging, especially as there are likely to be great variations across employees in terms of their perceptions, experiences and expectations regarding technology . These expectations and experiences may also differ from those of the developers and designers. Yet it is the match between user requirements and functionalities that lies at the heart of a successful learning technology. In Learning Layers we are exploring how creating and using Personas may help to design scalable technology for supporting informal learning in healthcare.