Wearable health patches are thin electronic devices that stick to the skin and measure body signals during daily life. They matter because they can track health continuously instead of only during a clinic visit. A patch may measure heart rate, temperature, motion, sweat chemistry, or blood oxygen trends depending on its sensors.
This can help patients, athletes, and clinicians notice changes earlier and make better decisions.
Key Facts
- Heart rate = number of beats counted ÷ time in minutes.
- Sampling rate f_s is the number of measurements recorded per second, measured in hertz.
- Ohm's law helps model simple sensor circuits: V = IR.
- Electrical power used by a patch is P = IV, where P is power, I is current, and V is voltage.
- Battery life can be estimated by time = battery capacity ÷ average current.
- A flexible patch often includes an adhesive layer, sensor layer, flexible circuit, power source, wireless transmitter, and protective top layer.
Vocabulary
- Biosensor
- A biosensor is a device that detects a biological signal or chemical and converts it into an electrical signal.
- Electrode
- An electrode is a conductive contact that picks up or delivers electrical signals at the skin or within a circuit.
- Sampling rate
- Sampling rate is how many times per second a device records a measurement.
- Hydrogel
- Hydrogel is a water-rich soft material often used to improve contact between skin and a sensor.
- Telemetry
- Telemetry is the wireless sending of measurement data from a device to another system for viewing or storage.
Common Mistakes to Avoid
- Confusing a wearable patch with a treatment device is wrong because many patches only measure signals and do not deliver medicine or therapy.
- Assuming every patch directly measures blood chemistry is wrong because many chemical patches analyze sweat or skin-surface fluids, which may not match blood values exactly.
- Ignoring sensor contact is wrong because loose adhesive, dry electrodes, or air gaps can add noise and reduce accuracy.
- Treating continuous data as automatically reliable is wrong because motion, sweat, temperature changes, and low battery can create artifacts that must be filtered or checked.
Practice Questions
- 1 A patch counts 72 heartbeats in 60 seconds. What is the heart rate in beats per minute?
- 2 A patch records temperature data at 2 samples per second for 5 minutes. How many total data points are collected?
- 3 A skin patch reports sudden heart rate spikes only during running, but not while the wearer is resting. Explain two reasons why the spikes could be real signals or measurement artifacts.