Fluid filter devices include at least one porous body. A grid of ring oscillator units and switches connect or disconnect the ring oscillator units to or from each other, such that the locations with low speed performance are identified according to frequencies of oscillation signals generated by rows and columns of ring oscillators respectively formed by operating the test circuit in two different modes. Each of the chip-scale circular polarizing filters is diced to have an edge that defines a polarization location index for the linear polarizer. The clip has first and second portions.