We present the results of an exptl. and theor. study on the optimum design of shear-force sensors, used in scanning probe microscopes. We have optimized a configuration consisting of a tuning-fork/fiber-tip assembly, achieving quality factors (Q) exceeding 8000, and have presented a theor. anal. of the design wherein the force holding the fiber and fork in contact is provided solely by elastic mech. deformation, which allows full control of the performance of the system. On this basis, we constructed a high-quality-factor configuration with the fiber glued onto the tuning fork. [on SciFinder (R)]