Breast cancer has become the most commonly diagnosed cancer worldwide and one of the leading causes of cancer deaths. However, it is not this primary tumour that causes the majority of deaths, but metastasis, which causes the tumour to spread to other organs in the body. This is why the early detection of breast cancer metastasis is of vital importance for the management and prediction of cancer progression. The entire metastatic process is linked to cancer plasticity and the epithelial-to-mesenchymal transition (EMT), which describes metastasis as a dynamic process by which cells of epithelial origin convert into cells bearing mesenchymal characteristics. Animal studies remain one of the sole means of assessing metastasis on development, however, the use of animals to study human systems is increasingly questioned due to ethics, cost and relevance concerns. In the past decade, in vitro models have been adapted apace to new culture methods, benefitting from advances in cell culture (in particular 3D cell culture) and organ-on-chip developments. Here, a bioelectronic device made of a conducting scaffold is presented as a powerful tool for the optical and electrical monitoring of cell growth and the EMT.