An integrated optofluidic droplet lens driven by a fast thermoelectric cooler

•A TEC device was applied to design the integration of liquid-droplet microlens.•The high-resolution 3D printing technology, which offers excellent topography flexibility, was used to fabricate a three-dimensional microfluidic chip.•A thermal-pneumatic-mechanical analysis was used to estimate the optimal air chamber design for allowable temperature change.•The thermal and optical response times were measured to prove the advancement of the liquid-droplet lens.•The dynamic liquid flow and images were confirmed, and the experiments demonstrated that the focal length varied from 17mm to 5mm when the temperature increased from 24 °C to 34 °C.