A process for manufacturing a micro-fluidic device, the device including a substrate made of thermoplastic polymer having a face called the upper face and a first micro-fluidic circuit that includes at least one aperture that opens onto the upper face, and a component bearing pads arranged to become anchored in the substrate on the periphery of the aperture, the process including the following steps: heating so that the anchoring pads of the component reach a temperature at least equal to the glass-transition temperature of the substrate; fastening the component to the substrate by embedding then anchoring its pads in the substrate.