Wireless LC Sensor Reader Using Spike Pulses
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Solution Overview
Problem
Existing sensor readers for monitoring blood pressure using LC sensors are inefficient due to the need for high-power RF amplifiers, are bulky, and cannot simultaneously read multiple resonant frequencies, leading to increased complexity and cost.
Innovation Solution
A wireless sensor reader that uses a capacitor discharging technique to generate a spike-shaped, low-energy excitation pulse, eliminating the need for a wide-band RF signal generator and allowing simultaneous detection of multiple resonant frequencies without a high-power RF amplifier, utilizing a single loop antenna and digital signal processing to compute resonant frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a wide-band RF signal generator and high-power RF amplifier are used to detect resonant frequency changes, then the measurement accuracy and signal-to-noise ratio are improved, but the device becomes bulky and energy-consuming
Solution Approach 1:
The patent extracts the resonant frequency detection function from the complex RF signal generation and amplification system. By using a simple pulse generator and listening for the sensor's natural ring-down oscillation, the system eliminates the need for wide-band RF signal generators and high-power amplifiers while maintaining measurement accuracy.
Solution Approach 2:
Instead of actively driving the sensor at its resonant frequency using complex RF generation and amplification, the patent inverts the approach by applying a broad-band pulse and passively listening for the sensor's natural resonant response. This inversion simplifies the reader system while preserving measurement capability.
2Adaptability or versatility
If multiple PLL circuits are used to read multiple resonant frequencies simultaneously, then the versatility of reading multiple sensors is improved, but the device complexity and cost increase
Solution Approach 1:
The patent creates a universal reading method where a single pulse generator and receiver system can read multiple sensors with different resonant frequencies. The broad-band pulse excites all sensors simultaneously, and the system identifies each sensor's unique resonant frequency through spectral analysis of the ring-down signals, eliminating the need for multiple dedicated PLL circuits.
Solution Approach 2:
The patent applies excessive action by using a broad-band pulse that excites the entire frequency spectrum rather than targeting specific frequencies. This excessive excitation allows the system to capture resonant frequencies from multiple sensors simultaneously through spectral analysis, avoiding the need for multiple targeted PLL circuits.
3Device complexity
If a fixed center frequency with limited bandwidth is used, then the reader circuitry is simplified, but the frequency response coverage is limited and SNR is non-uniform
Solution Approach 1:
The patent introduces dynamic frequency analysis by using a Fast Fourier Transform (FFT) to dynamically identify the resonant frequency of each sensor after excitation. This dynamic approach allows the simple pulse-based system to adapt to different resonant frequencies without requiring complex fixed-frequency tuning circuitry, achieving both simplicity and broad frequency coverage.
Solution Approach 2:
The patent changes the excitation parameter from continuous narrow-band RF signals to broad-band pulses. This parameter change allows the simple reader circuitry to cover a wide frequency range by analyzing the spectral content of the ring-down signals through FFT, achieving uniform frequency response coverage without complex circuitry.
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 results in a compact, energy-efficient sensor reader that can accurately measure blood pressure with improved sensitivity and reduced measurement error, capable of reading multiple resonant frequencies simultaneously, thus enhancing energy efficiency and cost-effectiveness.
Implementation Method 1
an antenna configured to transmit the excitation energy pulse to excite a wireless sensor, causing the wireless sensor to emit a ring-down signal
Implementation Method 2
the antenna having a ferrite backing shield
Data Source
AI summary
An energy-efficient, wide-band, and compact wireless sensor reader remotely interrogates an implanted wireless inductive-capacitive (LC) sensor in order to measure a physiologic parameter of interest within a human body. The wireless sensor reader generates an instantaneous, spike-shaped, high-amplitude, low-energy pulse to excite the wireless LC sensor, causing it to emit a ring-down signal. The wireless sensor reader subsequently receives, amplifies, and filters the ring-down signal. Next, the wireless sensor reader digitizes the ring-down signal and transfers the digitized ring-down signal to a processing unit. The processing unit computes a Fast Fourier Transform (FFT) of the digitized ring-down signal and then locates the resonant frequency of the LC sensor using a threshold peak detection technique.