Optical MEMS Intracranial Probe for EMI-Free Pressure and Temperature Sensing
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Solution Overview
Problem
Existing ICP and ICT monitors are affected by electromagnetic interference and optical fiber bending, and existing ICT sensors are electric-based, which can be disrupted by strong electromagnetic fields.
Innovation Solution
An optical MEMS based ICP and ICT monitor using a broadband light source, tunable optical filter, optical etalon, optical receivers, and optical couplers, with integrated ICP and ICT sensors connected by single mode optical fibers, utilizing reflection spectra to measure ICP and ICT without electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric-based MEMS ICP monitors are used, then ICP monitoring capability is achieved, but electromagnetic interference causes false images and probe displacement
Solution Approach 1:
The patent replaces electric-based MEMS sensing with optical-based sensing. The optical ICP monitor uses optical fibers to transmit light to and from the sensing membrane, eliminating electrical components that are susceptible to electromagnetic interference. This substitution of electrical systems with optical systems resolves the contradiction by maintaining monitoring reliability while avoiding electromagnetic interference vulnerabilities.
Solution Approach 2:
The patent introduces optical fibers as intermediary elements between the light source/detector and the ICP sensing membrane. These optical fibers transmit optical signals without being affected by electromagnetic fields, serving as an intermediary that protects the sensing system from electromagnetic interference while maintaining the ICP monitoring function.
2Object-affected harmful factors
If optical fiber is used for ICP monitoring, then electromagnetic interference is avoided, but optical fiber bending changes light power and interferes with measurement
Solution Approach 1:
The patent transitions from measuring light power intensity to measuring light wavelength characteristics for ICP detection. By using wavelength-based measurement instead of power-based measurement, the system becomes insensitive to optical fiber bending losses, as bending affects power transmission but not the spectral wavelength positions. This parameter change resolves the contradiction by maintaining electromagnetic interference resistance while eliminating bending-induced measurement errors.
Solution Approach 2:
The patent uses a broadband light source that provides excessive spectral coverage beyond what is strictly necessary for the measurement. This allows the system to identify and isolate the specific wavelength features related to ICP changes from other wavelength variations caused by fiber bending, effectively filtering out the harmful bending effects while maintaining electromagnetic interference resistance.
3Temperature
If electric-based thermistors are used for ICT monitoring, then temperature sensing is achieved, but electromagnetic wave disrupts the sensing
Solution Approach 1:
The patent replaces electric-based thermistor temperature sensing with optical-based temperature sensing. The optical ICT sensor uses the wavelength-dependent absorption or fluorescence properties of optical materials that change with temperature, eliminating electrical components. This substitution maintains temperature sensing capability while avoiding electromagnetic wave disruption, as optical signals are not affected by electromagnetic fields in the same way electrical signals are.
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 system provides accurate and reliable ICP and ICT monitoring by using optical methods, unaffected by electromagnetic interference and optical fiber bending, with integrated sensors in a single probe.
Implementation Method 1
an optical etalon with an absolute wavelength mark is configured to generate a periodic spectrum as a ruler to measure the absolute peak or depression wavelength
Implementation Method 2
the ICP sensor is a MEMS resonator structure formed by a single mode optical fiber a MEMS membrane and a glass substrate, and a tip of the single mode optical fiber acts as a mirror; the MEMS membrane deforms slightly due to the ICP
Implementation Method 3
The light is directed by optical fiber and hits the membrane of the ICP sensor
Implementation Method 4
ICP is obtained by a depression wavelength of a reflection spectrum of the ICP sensor, the depression wavelength is obtained by comparing with a periodic spectrum with an absolute wavelength mark of an optical etalon
Data Source
AI summary
The present invention discloses an optical MEMS based intracranial pressure (ICP) and intracranial temperature (ICT) monitor, comprising: a broadband light source, a tunable optical filter (TOF), an optical etalon, a plurality of optical receivers, a plurality of optical couplers, and a probe; wherein the probe comprises an ICP sensor and an ICT sensor; ICP is obtained by a depression wavelength of a reflection spectrum of the ICP sensor, the depression wavelength is obtained by comparing with a periodic spectrum with an absolute wavelength mark of an optical etalon; and ICT is obtained by a peak wavelength of a reflection spectrum of the ICT sensor, the peak wavelength is obtained by comparing with a periodic spectrum with an absolute wavelength mark of an optical etalon. The present application can precisely monitor ICP and ICT.