Blinking Multiplexed LED Strain and Chemical Sensors for Implants
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Solution Overview
Problem
Current methods for assessing bone health and detecting early-stage infections near orthopedic implants are inadequate, as they lack non-invasive, widely applicable tests for load-bearing capabilities and often require expensive and radiation-intensive imaging or impractical devices, leading to delayed diagnosis and increased morbidity and mortality.
Innovation Solution
Implantable sensors with light-emitting diodes (LEDs) that can be read non-invasively using conventional methods, capable of measuring strain and local chemical concentrations, such as pH and oxygen levels, to assess bone health and detect early signs of infection, utilizing multiple LEDs with different frequencies and reference LEDs to account for spectral distortion and improve sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods (X-ray, CT) are used to assess bone health, then structural information can be obtained, but the methods are expensive, expose patients to radiation, and cannot detect early-stage infection or mechanical properties
Solution Approach 1:
The patent replaces conventional imaging systems (X-ray, CT) with an optical sensing system using LEDs and photodetectors. This substitution eliminates radiation exposure while enabling detection of both structural changes and chemical markers of infection through optical signals that can penetrate tissue and be detected externally.
Solution Approach 2:
The patent introduces optical signals as an intermediary between the implant site and external detectors. LEDs embedded in or near the implant emit light that interacts with tissue and infection markers, allowing indirect detection of infection and bone health without direct contact or radiation exposure to the patient.
2Adaptability or versatility
If multiple sensors are implanted to monitor multiple parameters, then comprehensive data can be collected, but device complexity and surgical implantation difficulty increase
Solution Approach 1:
The patent designs a universal sensor platform where a single implantable device can monitor multiple parameters (pH, temperature, infection markers) using different optical sensors and LEDs. This multi-functional approach allows comprehensive monitoring without requiring multiple separate implants, reducing overall system complexity.
Solution Approach 2:
The patent combines multiple sensing functions into a single integrated implantable device. By merging pH sensors, temperature sensors, and infection detection capabilities into one unit with shared power and communication systems, the patent reduces the number of surgical implantations required while maintaining comprehensive monitoring capability.
3Reliability
If continuous monitoring is performed to detect early infection, then timely intervention is possible, but energy consumption increases
Solution Approach 1:
The patent implements periodic sampling of sensor data rather than truly continuous monitoring. The optical sensors take measurements at intervals, allowing early detection of infection trends while significantly reducing power consumption compared to continuous operation. This periodic action maintains detection reliability by capturing changes over time.
Solution Approach 2:
The patent employs threshold-based triggering where the system automatically increases monitoring frequency when abnormal conditions are detected. During normal operation, low-power periodic sampling is used, but when pH or other parameters approach concerning thresholds, the system self-adjusts to more frequent monitoring, optimizing energy use based on actual patient needs.
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
Enables accurate, non-invasive monitoring of bone healing and early infection detection, allowing for timely intervention and reducing the risk of re-fracture, hardware failure, and surgical complications, while being cost-effective and accessible for conventional use.
Implementation Method 1
The device includes a light emitting diode (LED)... multiple LEDs with different frequencies
Implementation Method 2
capable of measuring strain and local chemical concentrations... utilizing multiple LEDs with different frequencies and reference LEDs to account for spectral distortion
Data Source
AI summary
Implantable sensors are described that can be utilized in conjunction with orthopedic implants for monitoring fracture healing and detecting local chemical concentrations to detect and monitor implant associated infection. The sensors can include strain gauges, electrochemical, or spectrochemical sensors that can be read transdermally using a single photodetector. Sensors can be affixed to implantable support devices so as to non-invasively monitor the effect of load on the implant to provide a quantitative assessment of when a fracture is sufficiently healed to allow safe weight-bearing upon the limb. Alternatively, sensors can monitor the local concentration of infection biomarkers, for instance to monitor the implant area for early stage infection.