Picomole Dopamine Detection Using Optical Chips

Precise detection of dopamine is essential in medical applications to diagnose many diseases such as Parkinson's disease. Here, a new optical approach based on surface plasmon resonance (SPR) is presented to detect dopamine down to 50 pM. A four-layer coating structure is developed including SU8 waveguide, platinum, platinum nanoparticles, and plastic in order to reach high sensitivity and selectivity. The device was examined for picomole concentration of dopamine, and extremely high sensitivity and linearity were observed. In addition, the device was configured to operate at high wavelength in range of 1450 to 1600 nm in order to achieve low power loss and high compatibility with normal optic fibers. Furthermore, the system was examined for higher concentrations with lower wavelength to investigate its sensitivity range. In addition, cross sensitivity for other blood substances such as acid ascorbic, glucose, and lysine was investigated and reported.