Abstract: The present invention relates to a portable device for the detection of analytes, in particular toxic substances, comprising at least a whole-cell biosensor with cells immobilized onto a transparent and inert matrix that allows the maintenance of cell vitality. The matrix comprises a mixture of collagen and/or its enzyme degradation derivatives, a proteoglycan and a mixture of vinyl polymer and an optionally modified polysiloxane, and an orthosilicate. The biosensor can be a genetically modified cell that expresses luciferase as reporter gene.