RESUMO
This paper presents experimental force and buckling analysis of a compliant micro-displacement amplification mechanism fabricated using the commercially available PolyMUMPs process. The proposed mechanism proficiently amplifies displacement, at two output ends, with an optimal amplification factor of 7.2. Buckling analysis revealed that an amplification factor ranging from 2.8 to 11 may be achieved for an input displacement varying from 0.1 to 7.5 µm. Based on the analysis, the optimal value of the amplification factor is found to be 7.2 with an input displacement of 3.5 µm at the operational force of 60 µN having a buckling load factor (BLF) >1. Critical load magnitude is 187 µN having BLF = 1. Buckling occurred when loading exceeded the critical load value, having BLF <1, and the mechanism failed to produce a significant amplification factor. Static analysis showed that stresses produced are within the safe region, and the structural integrity of the mechanism is not compromised having a factor of safety of 1.4. Modal analysis predicted that the natural frequency of the desired mode is 35.47 kHz. Dynamic simulations, under 15 g dynamic load with a frequency range of 30-40 kHz, confirm the possibility of integrating the proposed mechanism with MEMS devices. Parametric optimization comprehends that length and angle are the two major geometric parameters that govern the working range, force, and amplification factor. For input displacements below 1 µm, the amplification factor is even higher, which is highly beneficial for amplifying small displacements. Static, modal, and dynamic analyses of the designed mechanism have been carried out using finite element method based commercial software IntelliSuite®. The experimental results showed that this mechanism can provide the same amplified displacement at two output points and is self-sufficient to be incorporated as an intermediate compliant mechanism for enhancing the output in the case of both static and dynamic micro-devices.
RESUMO
This research paper presents design and analysis of the multi-jaw microgripper that can manipulate microbiological organisms and species, cell probing and measurement, biomedical sample sorting, and preparation. Four jaws, actuated with a single thermal chevron actuator, can grip microbiological species ranging from 300 to 700 µm, 1 to 340 µm, 100 µm pool, and 1 to 120 µm spongy cells, respectively. Jaws are designed in such a way that they can grip regular, irregular, and spongy shaped biological species and their organelles. Parametric analysis of the microgripper exhibited that at 10 V, the efficiency of the thermal actuator is at maximum with respect to displacement, force, and temperature. To enhance displacement to voltage ratio and increase the energy efficiency, a class 3 lever mechanism has been incorporated. The amplification factors at four jaws are 17.21, 13.82, 4.02, and 4.93, respectively. For controlled application of the force to microspecies, two electrostatic force sensors have been amalgamated with jaws having capacitive sensitivities of 1.59 nf/µm, 1.91 nf/µm, 17 nf/µm, and 14.5 nf/µm, respectively. Electrothermal, static, and electrostatic analyses have been carried out with the finite element methods based software IntelliSuite®. Stress magnitudes are within the limits of structural integrity of silicon having a factor of safety 2.5. Thermal analysis revealed that at a differential voltage of 10 V, the maximum temperature goes up to 425 °C. Buckling analysis results depicted that the critical load for the thermal actuator is 241 µN with the buckling load factor greater than unity. This paper focuses on microbiological applications only; however, the designed microgripper can be used to manipulate micro-objects, microstructures, microelectronics parts, and micro assembly.
