Limits on the existence of scalar interactions in the submillimeter range

Upper limits to the presence of scalar interactions are given in the Compton wavelength range around ${10}^{-4}$ m. The technique is based on the search for displacements induced on a micromechanical resonator in the presence of a dynamical gravitational field. This gives the strongest constraint on the existence of scalar particles in the mass range between ${10}^{-4}$ and ${10}^{-1}$ eV, with a minimum value of the coupling constant $\alpha <~8\times {10}^7$ at a Compton wavelength $\lambda =2\mathrm{}\times {10}^{-4}$ m.