Asymmetric fluid-structure dynamics in nanoscale imprint lithography

3.2.4 Force Sensing SystemIn order to characterize the forces during the squeezing or separationprocess, dynamic forces must be measured in real-time. Force sensors are placedin series with the DC Mike actuators and coupled to the flexure ring via universaljoints to prevent edge loading or bending moments. Consistent with the activestage design, these force sensors must be stiff in the lateral direction.PCB Piezotronics 208C02 piezoelectric quartz force sensors were usedto obtain force data. These piezoelectric force sensors can be used for dynamicforce measurements providing a fast response in both compression and tension.These sensors have a dynamic range of ±450 N, compression and tension.Furthermore, the stiffness of the sensors is comparable to solid steel, k = 1×10 9N/m.3.3 IMPLEMENTED DESIGNThe active stage kinematics or RPU stage is similar to the ideal RPBstage, which has been thoroughly analyzed using screw system theory. Figures3.8 and 3.9 show the active stage system prototype. This test bed can be used tostudy the effect of the etch barrier on the orientation alignment for passive,selectively compliant stages. Separation of the template from the UV-exposedetch barrier can also be studied using the active stage.49