Self-Powered P-SAW RF Signal Frequency Control
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Solution Overview
Problem
Existing radioisotope-powered MEMS devices face challenges in precise frequency control of RF signals due to low resonant cavity quality factor and variability in component dimensions and dielectric properties, leading to unreliable frequency measurement and noise issues.
Innovation Solution
A self-powered device incorporating a radioisotope-powered current impulse generator connected to a piezoelectric-surface acoustic wave (P-SAW) apparatus, where the P-SAW resonator frequency is determined by the gap between interdigitated electrodes, allowing for precise control and tuning of the RF signal frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resonant cavity is used for RF signal generation in radioisotope-powered MEMS devices, then the device can generate RF signals, but the frequency control precision deteriorates due to low quality factor and component variability
Solution Approach 1:
The patent replaces the mechanical resonant cavity system with a piezoelectric surface acoustic wave (P-SAW) resonator system. The P-SAW resonator uses piezoelectric materials to generate and control acoustic waves on a surface, providing much higher frequency stability and control precision. The piezoelectric effect allows for precise frequency tuning through voltage control, eliminating the quality factor limitations of traditional resonant cavities.
Solution Approach 2:
The patent employs parameter changes by utilizing the piezoelectric effect to dynamically adjust the resonant frequency of the P-SAW resonator. By applying voltage to the piezoelectric material, the physical dimensions and elastic properties change, enabling precise frequency control. This allows the system to maintain stable frequency operation despite variations in other components.
2Duration of action of moving object
If conventional batteries are used to power MEMS devices, then the devices can operate, but the device size increases and operating lifetime is limited to days or months
Solution Approach 1:
The patent implements a self-powered system where the MEMS device generates its own power through radioisotope decay. The radioisotope (such as Nickel-63) continuously emits beta particles that are collected by a charged-coupled device (CCD), generating electrical energy on-demand without requiring external power sources or batteries. This eliminates the need for battery replacement and significantly extends operating lifetime to years or decades.
Solution Approach 2:
The patent extracts power generation capability directly from the MEMS device structure itself by integrating a radioisotope source and charge collection mechanism within the device. This eliminates the need for separate battery components, reducing overall device volume while providing long-term power supply. The radioisotope is mounted to the substrate and integrated with the MEMS structure, creating a compact self-powered system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise frequency control of RF signals, improving signal-to-noise ratio and enabling reliable long-distance transmission with a narrowband pulse measurement, suitable for applications like autonomous transponders and sensors.
Implementation Method 1
the energy carried by particles emitted by radioactive decay in a radioisotope such as Nickel-63 is captured
Implementation Method 2
A piezoelectric element having output terminals is secured to the top surface of the cantilever so that the piezoelectric plate will flex and deform with the deformable cantilever
Implementation Method 3
As charge builds up on the absorber and the source, the electrostatic force between these elements increases, bending the cantilever beam
Implementation Method 4
The capacitance of the piezoelectric transducer element connected to the coil provides a resonant tank circuit that produces an electrical oscillation at a characteristic frequency
Data Source
AI summary
An autonomous, self-powered device includes a radioisotope-powered current impulse generator including a spring assembly comprising a cantilever, and a piezoelectric-surface acoustic wave (P-SAW) structure connected in parallel to the current impulse generator. Positive charges are accumulated on an electrically isolated 63Ni thin film due to the continuous emission of β-particles (electrons), which are collected on the cantilever. The accumulated charge eventually pulls the cantilever into the radioisotope thin-film until electrical discharge occurs. The electrical discharge generates a transient magnetic and electrical field that can excite the RF modes of a cavity in which the electrical discharge occurs. A piezoelectric-SAW resonator is connected to the discharge assembly to control the RF frequency output. A method for generating a tuned RF signal includes inputting an energy pulse to a P-SAW resonator, exciting the resonant frequency thereof, and outputting an RF signal having a frequency tuned to the resonator frequency.