High-index-contrast compact microdisk resonators in thermally evaporated ${\mathrm{As}}_2{\mathrm{S}}_3$ and ${\mathrm{Ge}}_{17}{\mathrm{Sb}}_{12}{\mathrm{S}}_{71}$ chalcogenide glass films are designed and fabricated using standard UV lithography and characterized. Our pulley coupler configuration demonstrates coupling of the resonators to monolithically integrated photonic wire waveguides without resorting to demanding fine-line lithography. Microdisk resonators in ${\mathrm{As}}_2{\mathrm{S}}_3$ support whispering-gallery-mode with cavity quality factors $\left(Q\right)$ exceeding $2\times {10}^5$ , the highest Q value reported in resonator structures in chalcogenide glasses to the best of our knowledge. We have successfully demonstrated a lab-on-a-chip prototype sensor device with the integration of our resonator with planar microfluidic systems. The sensor shows a refractive index sensitivity of $182\mathrm{nm}∕\mathrm{RIU}$ (refractive index unit) and a wavelength resolution of $0.1\mathrm{pm}$ through a resonant peak fit. This corresponds to a refractive index detection limit of $8\times {10}^{-7}$ RIU at $1550\mathrm{nm}$ in wavelength, which could be further improved by shifting the operating wavelength to a region where water absorption is reduced.