A microfluidic system utilizing molecularly imprinted polymer films for amperometric detection of morphine

This study reports a microfluidic system for detecting morphine (MO) using a combination of a molecularly imprinted polymer (MIP) and electrochemical sensing techniques. A monomer, called 3,4-ethylenedioxythiophene (EDOT), was used to mix with morphine molecules through an electropolymerization process on a sensing electrode. The modified MIP-PEDOT (poly-ethylenedioxythiophene as the imprinting polymer with MO as the template) electrode was then used for detecting the morphine via the amperometric method. Key components including MIP films, a PDMS (polydimethylsiloxane)-based microchannel, a peristaltic micropump, microvalves and sensing microelectrodes were integrated to form a new microfluidic system for morphine sensing utilizing MEMS (micro-electro-mechanical-systems) technologies. The morphine samples were automatically transported to the MIP-PEDOT sensing electrode using the peristaltic micropump. Then, the morphine was detected using the electrochemical method. Experimental data show that the sensitivity of the MIP-PEDOT morphine sensor is 171.5 μA/cm² mM in detecting morphine concentration ranging from 0.01 to 0.2 mM at a flow rate of 92.3 μl/min. The novel combination of microfluidics, MIP, and electrochemical sensing technologies provides a promising approach for highly sensitive, highly selective morphine sensing with a low sample consumption rate. More importantly, the whole process can be performed in an automatic format by using the enabling microfluidic technology. A multi-functional electrochemical detection system is feasible using similar microfluidics/MIP/electrochemical technologies.