The PUR-TECH project aims to develop a technology for the purification of nucleic acids from biological fluids such as blood or saliva. In order to minimise false-positive diagnostic errors on liquid biopsies, our goal is to purify large volumes of biological fluids from 2 to 5 mL in short times of 2 to 10 minutes. With a purification yield of more than 80 %, we can isolate rare mutation events such as the onset of a residual disease. To meet this challenge, we propose to exploit the unique potential of µLAS technology, already patented 4 times nationally and internationally, which allows to dialyse a sample, concentrate and sort it in size by piloting electric and hydrodynamic fields. Our technological bet is the use of a calibrated hole filter and original supports obtained by 3D printing. Our research program is divided into a first phase of system validation within the LAAS-CNRS and is considering implementation in the clinical environment within the CRCT, with a view to better management of cohorts of patients with pancreatic cancers.