Overview
This lecture reviews the design, types, features, and applications of wearable biosensors for healthcare monitoring, highlighting non-invasive approaches for real-time biomarker detection in biological fluids like saliva, sweat, and tears.
Introduction to Wearable Biosensors
- Wearable biosensors (WBSs) are portable devices integrated with or attached to the body to monitor health parameters.
- WBSs enable real-time, non-invasive measurement of biomarkers in fluids such as saliva, sweat, and tears.
- Typical biosensors consist of a biorecognition element and a transducer that converts biological recognition into measurable signals.
- WBSs are classified into motion, biophysical, and biochemical sensors based on the parameters measured.
Types and Features of Wearable Devices
- Wearables can be categorized by design: bands/watches, textiles, headgear, and sensory devices.
- Wrist-mounted devices (bands, watches, patches) track activity, physiological signals, and specific analytes (e.g., glucose, sodium).
- Head-mounted devices (glasses, helmets) enable hands-free monitoring of heart rate, metabolites, and other health signals.
- Cavitas devices (contact lenses, mouthguards) access biomarkers in tear or saliva fluid.
- E-textiles/smart clothing integrate sensors into fabrics for continuous physiological monitoring.
Material and Functionality Advances
- Bio-multifunctional sensors use self-healing, biocompatible, and biodegradable materials for durability and safety.
- Microfluidic integration enables efficient sample collection and handling, especially in sweat-sensing devices.
- Colorimetric and electrochemical principles are the main transduction mechanisms used in wearable biosensors.
Applications in Biofluid Monitoring
- Saliva-based sensors (mouthguards, pacifiers) monitor metabolites like glucose, uric acid, and lactate non-invasively.
- Tear-based sensors (contact lenses, smart glasses) measure glucose and proteins for disease and metabolic monitoring.
- Sweat-based sensors (patches, tattoos, textiles) detect electrolytes, glucose, and lactate for fitness and disease management.
- Subcutaneous and implantable biosensors allow continuous measurement of blood and interstitial fluid markers.
Future Trends and Challenges
- Ongoing improvements focus on increasing precision, biocompatibility, sensitivity, and reliability.
- Integration of microfluidics and wireless technology is key to real-time, portable diagnostics.
- Translating proof-of-concept devices into commercial products requires solving issues like stability, calibration, and clinical validation.
Key Terms & Definitions
- Biosensor — A device that detects biological molecules using a biorecognition element and a transducer.
- Biorecognition element — A component (enzyme, antibody, etc.) that selectively interacts with a target analyte.
- Transducer — Converts a biological event into a measurable physical signal.
- Microfluidics — Miniaturized fluid handling systems integrated for sample processing.
- E-textiles — Fabrics embedded with electronic sensors for physiological monitoring.
- Self-healing material — A substance that can autonomously repair minor physical damage.
Action Items / Next Steps
- Review the various wearable biosensor types and examples.
- Understand the differences between colorimetric and electrochemical detection in wearables.
- Study key challenges in translating wearable biosensors from research to clinical practice.