Design and Fabrication of Vibration-Induced Electromagnetic Microgenerators

This work presents design and fabrication technologies on vibration-induced electromagnetic micro-generators using LTCC (Low temperature co-fire ceramic) processes. LTCC fabrication with some special advantages has simplistically processes and multilayer stack procedure, resulting in a micro-inducer can consist of the multilayer induction micro-coils and a helical ceramic micro-spring. Multilayer micro-coil structures can enhance the power output of generators. There are two types of microgenerator structures: the magnetic core-type generator (MCTG) and sided magnet-type generator (SMTG). In an MCTG, the magnetic field is generated by the interaction of a magnetic core element and a magnet in the center hole, whereas in an SMTG the magnetic field is generated by the microinduction coil on the sides of the magnetic element. The results confirmed that this fabrication procedure of the inducer using LTCC is valid. The fired microspring has a 100-µm beam width, a 100-µm beam interspace, a 1.7-mm innermost loop radius, and 5.5 unequal radius loops. In addition, the fired microcoil has a cross-sectional area of 90-µm (line-width) ? 10-µm (line-thickness). The entire volume of the meso-generator is 10 mm ? 10 mm ? 7.18 mm (approximately 718 mm3). The measurements were performed at a natural frequency of 69 Hz with maximal amplitude of 0.03 mm. The safe design of the double supporting beam was confirmed: the supporting beam has a maximal bending stress of 32 MPa and a lifetime of 1.95 ? 108 cycles when the vibration amplitude is at its maximum.