A skin patch (10, fig.1), for measuring a biometric parameter of a bodily fluid, comprises a hydrophilic sensing bead (24, fig.3) and a sensor including at least one electrode 30 embedded within the hydrophilic sensing bead. The sensor is configured to obtain data relating to the concentration of the hydrophilic sensing bead relating to the parameter. A transport section for transporting a bodily fluid contacts the hydrophilic sensing bead, and may be configured to control the rate at which the fluid is transported to the sensor. The transport section may comprise a plurality of capillary channels. A communication unit includes an input section communicating with the sensor via a connector, and an output section is configured to output the obtained data. When the fluid contacts the bead, the bead may be configured to equilibrate with the fluid. An equilibrate means may be provided to control the rate of equilibration. The bead may comprise a hydrogel 28. The sensor may be a potentiometric sensor and an amperometric sensor. The patch may be configured to undergo temperature calibration. A removal section may be provided for expelling the fluid and may comprise capillary channels.
