The present disclosure relates to semiconductor devices for detecting fluorescent particles. At least one embodiment relates to an integrated semiconductor device for detecting fluorescent tags. The device includes a first layer, a second layer, a third layer, a fourth layer, and a fifth layer. The first layer includes a detector element. The second layer includes a rejection filter. The third layer is fabricated from dielectric material. The fourth layer is an optical waveguide configured and positioned such that a top surface of the fourth layer is illuminated with an evanescent tail of excitation light guided by the optical waveguide when the fluorescent tags are present. The fifth layer includes a microfluidic channel. The optical waveguide is configured and positioned such that the microfluidic channel is illuminated with the evanescent tail. The detector element is positioned such that light from activated fluorescent tags can be received.