A universal electrochemical micro-sensor can be used either as a biosensor or an environmental sensor. Because of its small size and flexibility, the micro-sensor is suitable for continuous use to monitor fluids within a live subject, or as an environmental monitor. The micro-sensor can be formed on a reusable glass carrier substrate. A flexible polymer backing, together with a set of electrodes, forms a reservoir that contains an electrolytic fluid chemical reagent. During fabrication, the glass carrier substrate protects the fluid chemical reagent from degradation. A conductive micromesh further contains the reagent while allowing partial exposure to the ambient biological or atmospheric environment. The micromesh density can be altered to accommodate fluid reagents having different viscosities. Flexibility is achieved by attaching a thick polymer tape and peeling away the micro-sensor from the glass carrier substrate. The final structure is thereby transferred to the polymer tape, providing a flexible product.