This work presents a new architecture concept for microfluidic devices, which combines the conventional 3D printing fabrication process with the stable and precise integration of polymeric functional materials in small footprints within the microchannels in well-defined locations. The approach solves the assembly errors that normally occur during the integration of functional and/or sensing materials in hybrid microfluidic devices. The method was demonstrated by embedding four pH-sensitive ionogel microstructures along the main microfluidic channel of a complex 3D printed microfluidic device. The results showed that this microfluidic architecture, comprising the internal integration of sensing microstructures of diverse chemical compositions, highly enhanced the adhesion force between the microstructures and the 3D printed microfluidic device that contains them. In addition, the performance of this novel 3D printed pH sensor device was investigated using image analysis of the pH colour variations obtained from photos taken with a conventional camera.

The device presented accurate and repetitive pH responses in the 2 to 12 pH range without showing any type of device deterioration or lack of performance over time.