Solar concentrator systems rely on focusing a large collecting aperture onto a small one where a high efficiency solar cell is placed. The main drawback of concentrator systems is the need to track the direction of the sun. We report on the development of a trackfree planar solar concentrator which employs a self-adaptive light responsive mechanism. The working mechanism is based on optical trapping reflective particles dispersed into a liquid waveguide. The trapping effect experienced by the reflective particle at the focus of the collecting aperture effectively forces the particle to follow the direction of sunlight. The role of the reflective particle is to couple the cone of focused sunlight into a waveguide by total internal reflection (TIR) towards a solar cell placed at its edges. We report on preliminary experiments on metallic reflective particles and on gas-filled hollow glass particles that exhibit reflective properties by total internal reflection. We show promising results on vapor bubbles generated by the focused light which couple nearly 100% of the incoming light into waveguiding modes. The generated bubbles are stable and track the focal point.