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.