Seal whiskers have been well studied in view of their remarkable hydrodynamic trail tracking capability. The considerable variation in the whisker lengths indicates that the whiskers have different natural frequencies sensitive to various frequency bands of hydrodynamic stimuli. However, a thorough experimental investigation of the natural frequencies of seal whiskers has not been conducted before. Here, we develop a novel and low-cost methodology for easy measurements of the natural frequencies of seal whiskers using a 3D-printed MEMS cantilever sensor featuring a graphene nanoplatelet piezoresistor and a soft encapsulation of the whisker base at the distal end of the cantilever.
We demonstrate a pressure-sensing approach based on the resonant operation of a single-crystal Si cantilever positioned near a flexible, pressurized membrane. The membrane deflection perturbs the electrostatic force acting on the cantilever and consequently alters the beam's resonant frequency. Sensitivity was enhanced by tailoring the actuating force nonlinearities through fringing electrostatic fields. With our coupled micromechanical system, we achieved frequency sensitivity to pressure and displacement of ≈ 30 Hz/kPa and −4 Hz/nm, respectively. Our results indicate that the suggested approach may have applications not only for pressure measurements, but also in a broad range of microelectromechanical resonant inertial, force, mass and bio sensors.
This paper presents a low-complexity and low temperature (85°C) fabrication process for vibration energy harvesters. The process employs lamination steps to transfer thinned PZT thick sheets onto flexible polymeric substrates, using dry film photoresist. The influence of geometrical parameters on the device performance were assessed by FEM simulations (using COMSOL) and supported by experiments. Optimization of the output power was performed by modifying the neutral plane within the device and by using a localized seismic mass at the tip, which has resulted in an output power of 30 μW at 52 Hz and an acceleration of 1g. Finally, a low-complexity and fully polymeric package is proposed, which together with the harvester process are compatible with large area fabrication methods.
This work reports a preliminary study of a fully implantable biomimetic accommodative intraocular lens (IOL) structured as a MEMS-valved endocapsular balloon. The biomimetic accommodative IOL is modeled after the geometry of a 29-year-old human lens and fabricated using only biocompatible materials. Successful accommodation, or focusing ability of the lens, is demonstrated in an objective benchtop test bed with enucleated porcine eyes. After surgical implantation of the lens, the focusing muscles of the eye are stretched in a manner consistent with prior work to demonstrate a change in focal power as the muscle is stretched in a manner similar to the natural lens. This work also includes detailed surgical procedures for the insertion and inflation of the lens.
