7 type of Biosensors in Wearables: ECG, EEG, PPG, and More (Part 2)

Wearable medical devices have transformed healthcare by providing real-time monitoring and personalized health insights. In this article, we continue exploring key biosensors in wearables, focusing on Bioimpedance Analysis (BIA), Temperature Sensors, Galvanic Skin Response (GSR), and Accelerometers.

1) Bioimpedance Sensor

What is a Bioimpedance Sensor?

A Bioimpedance Sensor is a device used to measure the electrical impedance of biological tissues by applying a small alternating current. This sensor helps assess various physiological parameters such as body composition, hydration levels, and cardiac function.

Bioimpedance Sensor Accuracy and Applications

The accuracy of a bioimpedance sensor depends on factors such as signal frequency, electrode placement, and device calibration. Bioimpedance Sensor Accuracy is critical in medical diagnostics, wearable health devices, and research applications.

Key Metrics:

• Resistance (R): Represents opposition to electrical current, primarily linked to body water content.
• Reactance (Xc): Reflects the capacitive properties of cells and tissues.
• Phase Angle (PA): An indicator of cellular health and overall physiological status.

Bioimpedance Sensor Applications:

• Hydration monitoring: Ensures proper fluid balance for athletes and medical patients.
• Cardiac output estimation: Assists in monitoring heart function in disease management.
• Glucose monitoring: Ongoing research aims to enable non-invasive glucose tracking using BIA.
• Muscle mass analysis: Applied in fitness tracking and rehabilitation programs.

2) Temperature Sensors

What is the Sensor for Body Temperature?

Wearable temperature sensors continuously track skin or core body temperature, providing insights into metabolism, stress levels, and potential infections. These sensors are integrated into devices like smartwatches and fitness bands.

Comparing Medical Temperature Sensors with ISO 13485 and Apple Watch Body Temperature Sensors

A medical temperature sensor designed under ISO 13485 meets stringent regulatory standards for accuracy and reliability. In contrast, the body temperature sensor in the Apple Watch focuses more on wellness tracking rather than precise medical diagnosis. Medical-grade sensors are used in clinical environments for fever detection, ovulation tracking, and remote patient monitoring.

Key Metrics:

• Accuracy: Medical sensors must maintain ±0.1°C precision.
• Response time: Determines how quickly temperature changes are detected.
• Measurement range: Typically from 32°C to 42°C for medical applications.

Medical Temperature Sensor Applications

Wearable medical temperature sensor applications include:

• Fever detection: Continuous monitoring for early illness detection.
• Ovulation and fertility tracking: Helps individuals plan pregnancy with precise temperature tracking.
• Stress and metabolic rate monitoring: Temperature variations provide insights into body response.
• Remote patient monitoring: Allows healthcare providers to track temperature trends in patients with chronic diseases.

3) Galvanic Skin Response (GSR)

What is Galvanic Skin Response (GSR) Sensor?

A Galvanic Skin Response (GSR) sensor measures the electrical conductance of the skin, which varies based on sweat gland activity. It provides insights into emotional states, stress levels, and cognitive load.

Galvanic Skin Response Applications

Galvanic Skin Response Applications are found in stress management wearables, mental health monitoring, and lie detection. GSR is often combined with other biosensors to enhance emotional and physiological analysis.

Key Metrics:

• Skin conductance level (SCL): Measures the baseline conductivity over time.
• Skin conductance response (SCR): Captures transient spikes in conductivity linked to stimuli.
• Response latency: Measures how quickly skin conductance changes after a stimulus.

Applications:

• Stress and emotion tracking: Used in mental health applications to assess anxiety levels.
• Sleep monitoring: Helps in evaluating sleep quality based on stress responses.
• Cognitive load assessment: Used in research and UX design to study user engagement.
• Medical diagnostics: Helps in monitoring autonomic nervous system activity.

4) Accelerometers

What is an Accelerometer in a Medical Device?

An accelerometer in a medical device detects motion and orientation, allowing for activity tracking, posture monitoring, and fall detection. It is a crucial component in wearable health technology.

Accelerometer in Wearables

An accelerometer wearable is embedded in smartwatches, fitness bands, and medical monitoring devices to track movement patterns, step counts, and even tremors in Parkinson’s patients.

Key Metrics:

• Acceleration (m/s²): Measures the rate of change in velocity.
• Frequency response: Determines sensitivity to different movement speeds.
• Power consumption: Crucial for wearable battery efficiency.
• Resolution and sensitivity: Affects the precision of motion tracking.

Accelerometer in Medical Applications

The accelerometer in medical applications helps detect irregular movement patterns, monitor post-surgery recovery, and assist in elderly fall detection systems. By analyzing movement data, healthcare providers can gain valuable insights into a patient’s mobility and overall health status.

Applications:

• Fall detection for elderly care: Alerts caregivers in case of sudden falls.
• Parkinson’s disease monitoring: Tracks tremors and movement patterns.
• Posture correction: Helps users maintain correct posture.
• Rehabilitation tracking: Assists in recovery from injuries and surgeries.

ITR VN - A trusted tech hub in MedTech and Digital Health

At ITR VN, we specialize in MedTech and Digital Health, providing full-cycle development from Proof of Concept to Mass Production. With expertise in biosensor integration, we help clients build high-precision wearable health solutions that meet FDA compliance and ISO 13485 certification.

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