Radioisotope-powered-actuated MEMS Energy Collector Research

Wireless sensor nodes deployed in remote and inaccessible locations need long lifetime power sources to prevent cost prohibitive periodic replacement. This paper presents two kinds of conversion principles of isotope radiation energy into electricity. They are the electrostatic principle of radiation energy collection and piezoelectric principle of radiation energy collection.Electrostatic radiation energy collection principle is that the using of isotope nickel-63beta radiation energy to make parallel suspension-quality boards into free damped vibration, and then through the variable capacitance circuit to realize the charge-discharge oscillation cycle so as to realize the conversion of electrical energy;Piezoelectric radiation energy collection principle is to use the same nickel-63beta radiation energy to make the cantilever beam-quality into free damped vibration, and then through the electric potential difference of piezoelectric effect discharge through an external circuit implementation cycle.First of all,In view of the electrostatic collecting principle,straight arm cantilever beam structure is designed.In view of the piezoelectric collection principle,L cantilever beam structure is designed.Then motion and process of energy conversion of two kinds of principle are analyzed.By analysing the motion of two kinds of principles and the energy conversion process of two kinds of principles,the motion state and output equations of the two structures is given,which can be simulated with Matlab/Simulink to output characteristic and Ansys to the structure optimization design.The result of simulation shows that this design of electrostatic collection structure which is in the first order natural frequency of500Hz, the distance between the two plates is75um, external resistance is R=S4κΩ,the maximum average power output is P=0.416//μW, conversion efficiency can reach8.25%; And piezoelectric collection wich in the thickness of the beam is Tsi=30μm, length of the mass is Lm=5658μm, mass thickness is507μm,external resistance R=915.6Ω,the average output power will be is P=6.955//μW,and output voltage will be U=0.05123v.Finally, the process for electrostatic MEMS energy harvesting devices radiation processing technology were explored.