A palm-size portable μNMR relaxometer system for performing multi-step multi-sample chemical/biological assays, comprising a PCB having a CMOS μNMR transceiver and a DMF device integrated thereon. A portable magnet has an inner gap configured to at least partially receive the DMF device. The DMF device comprises a platform of electrodes including a sensing site and receives one or more samples for analysis at an electrode and automatically transports the one or more samples on individual paths sequentially to the sensing site, for performing sensing on each sample sequentially. A Butterfly coil disposed on the PCB and underneath the DMF device and is at least partially received in the inner gap. The Butterfly coil excites the sample at the μNMR sensing site by transducing a magnetic field produced at the sensing site to an electrical signal which is processed by the CMOS μNMR transceiver to produce an analytical signal.