There is currently an explosion in the number and range of new devices coming onto the technology market that use digital sensor technology to track aspects of human behaviour. In this article, we present and exemplify a three-stage model for the application of digital sensor technology in applied linguistics that we have developed, namely, Technology-Problem-Iterative Development and Research. We present three projects that have used this model. In the first and second, a language learning environment was facilitated and tracked by digital sensor technology, while in the second and third projects, the technology enabled multimodal data collection and analysis. All projects investigated how a digital learning environment might be designed, implemented, and evaluated. The research focus has been on how to record and analyse the process of language learning through spoken interaction using digital sensor technology. This model is amenable to a variety of methodological approaches, as we see conversation analysis used in the first two projects and multimodal corpus linguistics in the third.