A microneedle-based resonant sensor system for continuous, wireless monitoring of wound and physiological states

This technology uses gold-coated microneedles and wireless sensors to directly sample wound fluid, detecting infection and other changes in real time. Data is analyzed with machine learning and sent to clinicians for early, continuous wound monitoring.

Background

Wound monitoring is a critical aspect of healthcare, especially for patients recovering from surgery or those with chronic wounds. Early detection of infection and timely intervention can significantly improve patient outcomes and reduce healthcare costs. Traditionally, clinicians rely on visual inspection, patient-reported symptoms, and intermittent measurements of wound temperature or pH to assess wound status. However, these methods are often subjective, infrequent, and may not capture subtle physiological changes that precede infection or complications. As a result, there is a growing need for continuous, objective, and minimally invasive monitoring solutions that can provide real-time insights into wound healing and infection risk.

Current approaches to wound monitoring face several limitations that hinder their effectiveness. Electrochemical sensors, while capable of detecting specific biomarkers, are prone to degradation over time and can suffer from molecular interference, reducing their reliability for long-term use. Methods that extract interstitial fluid (ISF) using absorptive dressings or microfluidic channels often experience analyte loss and may not effectively replace or sample ISF, leading to inaccurate readings. Furthermore, existing technologies typically require direct contact with the wound or rely on external measurements, which can be insensitive to early or subtle changes in wound physiology. These shortcomings highlight the need for a more robust, sensitive, and direct method for continuous wound assessment, particularly for detecting early signs of infection and monitoring wound healing dynamics.

Technology description

This technology is a microneedle-based resonant sensor system designed for continuous, real-time monitoring of wound sites by directly sampling interstitial fluid (ISF) beneath the skin. The system features gold-coated polymer microneedles configured as parallel-plate capacitors, integrated with a resonant sensor coil and loop antenna.

When deployed, microneedles penetrate the tissue to access ISF, and the sensor detects changes in the fluid’s dielectric properties—such as those caused by shifts in pH, ionic concentration, temperature, and tissue swelling—by measuring variations in resonant frequency using RF impedance spectroscopy. An interrogator circuit initiates a frequency sweep and wirelessly collects the sensor’s response, which is then transmitted to a mobile device and cloud platform. Advanced machine learning models process this data to classify wound states and alert clinicians or patients to changes, enabling early infection detection and more precise wound management.

What differentiates this solution is its direct, continuous access to interstitial fluid via minimally invasive microneedles, which eliminates the need for fluid transport through microchannels or absorptive dressings—common sources of analyte loss and signal degradation in existing technologies. By adapting NASA’s SansEC resonant sensor technology and optimizing the microneedle array through electromagnetic simulations, the system achieves significantly higher sensitivity, reduced signal variance, and improved quality factor compared to prior planar designs.

The modular, wireless design allows for scalable deployment across various wound types and body sites, while the integration of machine learning enables personalized, combinatorial analysis of multiple biomarkers. This approach not only advances wound monitoring but also opens pathways for broader physiological monitoring applications, such as stress hormone detection and continuous glucose monitoring, setting it apart from conventional electrochemical and optical sensors.

Benefits

Enables continuous, real-time monitoring of wound interstitial fluid for early infection detection
Direct sampling of interstitial fluid via gold-coated microneedles improves sensitivity and reduces signal variance
Wireless, low-cost sensor design allows remote data transmission and integration with mobile/cloud platforms
Machine learning analysis provides accurate classification of wound states and prediction of biomarkers like pH and temperature
Improved sensor design offers higher quality factor and reduced dependence on fluid volume or distance
Non-invasive and minimally irritating due to optimized microneedle geometry and polymer materials
Potentially adaptable for monitoring other physiological parameters such as cortisol and glucose
Scalable and modular sensor array design suitable for various wound types and clinical applications

Commercial applications

Remote wound infection monitoring
Continuous physiological state tracking
Consumer health wearable sensors
Veterinary wound assessment
Cortisol level monitoring

Additional information

A microneedle-based resonant sensor system utilizes gold-coated polymer microneedles as a parallel-plate capacitor, integrated with a coil and antenna. It directly samples interstitial fluid, employing RF impedance spectroscopy to detect dielectric property variations (ionic concentration, pH, temperature, tissue swelling) via resonant frequency shifts. An interrogator circuit and machine learning classify physiological states for continuous intradermal monitoring.