Polymer biophotonic lab-on-chip devices with integrated organic semiconductor lasers

Abstract

We present optofluidic lab-on-a-chip devices (LOCs) for single use as disposables. In our approach we are aiming for systems out of poly(methyl methacrylate) (PMMA) that integrate (a) organic lasers, (b) optical waveguides, (c) microfluidic channels, (d) surface functionalization, and (e) fluorescence excitation on one single chip. We are utilizing mass production techniques to show the applicability of this approach by avoiding electrical interconnects but using optical and fluidic interfaces only. With our experiments we can show the feasibility of this approach by respectively combining two consecutive elements (a - e) of the path of light: Organic semiconductor lasers are integrated by evaporating a thin film of photoactive material on top of a distributed feedback (DFB) grating. For this purpose, grating masters are replicated by hot embossing into PMMA bulk material. The lasing wavelength in the visible light regime is tuned by altering the thickness of the vacuum deposited organic semiconductor active material or the DFB grating period. Emitted light from the DFB laser is coupled into polymer strip optical waveguides realized by Deep UV lithography. The waveguides allow optical guidance to a microfluidic channel. Tailored surface functionalization in the microfluidic channel by Dip-Pen Nanolithography (DPN) enables the local excitation of fluorescent markers and thus a detection of selected components in biomedical or environmentally relevant fluids.