Cu-based Metal Organic Frameworks (MOF) microdevices are applied in sampling and preconcentration of nerve agents (NAs) diluted in gaseous streams. An in-situ electrochemical assisted synthesis of Cu-BTC thick film is carried out to functionalize a Cu modified glass substrate. This simple, rapid, reproducible and easy to integrate MOF synthesis approach, enables the microfabrication of functional microprenconcentrators with large BET surface area (above 2000 cm2) and active pore volume (above 90 nanoliters) for the efficient adsorption of nerve agent molecules along the microfluidic channel 2.5 cm in length. Equilibrium adsorption capacity of the bulk material has been characterized through thermogravimetric analysis after exposure to controlled atmospheres of a sarin gas surrogate, dimethyl methylphosphonate (DMMP), in both dry and humid conditions (30% RH at 293 K). Breakthrough tests at ppm level (162 mg/m3) reveal equilibrium adsorption capacities up to 691 mg/g. The preconcentration performance of such µ-devices when dealing with highly diluted surrogate atmosphere, i.e. 520 ppbV (2.6 mg/m3) at 298 K, leads to preconcentration coefficients up to 171 for sample volume up to 600 STP cm3. We demonstrate the potentialities of Cu-BTC micropreconcentrators as smart first responder tools for “on field” detection of nerve agents in gas phase at relevant conditions.