The increase in instantaneous luminosity at the HL-LHC experiments will in general have a severe impact on event reconstruction. Original tracking capabilities could however be restored by measuring charged-particle tracks with picosecond precision. Within the TimeSPOT initiative we are developing innovative 3D pixels with the aim to build a demo mini tracker using 55µm x 55µm silicon pixels with a required time resolution of better than 50 ps per hit. A first batch of sensors was produced in 2019 by FBK in Trento, Italy. Different structures, designed on the basis of different electrodes geometries optimized with detailed simulations, were tested in 2019. A high-density trench-type square pixel layout was found to be particularly interesting from the point of view of timing performances. In this seminar results on the sensor time resolution measured both in the laboratory, with pulsed lasers and radioactive sources, and with charged hadrons at the PSI πM1 beamline in October 2019 will be presented. During these tests time resolutions of about 20 ps per hit have been measured, a result that could further be improved because it is still limited by the front-end electronics used.