As the new generation of designers face more complex design issues, the forms of design research start to shift towards a user-centred approach to problem-solving. The cooperation and communication among various fields and specialisations are becoming more complex; in many practical design cases, in particular, technology developers face challenges in deciphering the creative ideas of designers and the needs and restraints of users, society, law and science. The emergence of integrative design based on a wide range of disciplines has prompted discussion and exploration among various participants. The direction of contemporary design research has already transformed from one based on production of artefact to one focused on the integration of varied knowledge and fields at different stages. We examine such design research based on a problem-driven approach in two case studies characterised by interdisciplinary collaboration for solving complex problems. We focus on the transformation and implementation of integrative design research methods and suggest a "reflection-in-action" problem-solving process for strengthening the capabilities of multidisciplinary design research.