Stay aware. Stay cool. Stay safe.

ThermoGuard is a wearable smartwatch and iPhone app that helps people in the Blacktown area recognise heat-stress risk early and respond before it gets serious.

See how it works

The problem: heat stress

Heat stress happens when the body gains heat faster than it can lose it. It is a real risk across the Blacktown Local Government Area, which regularly runs hotter than coastal Sydney.

37°C

Where it starts

Heat stress is when the body’s internal temperature rises above about 37°C, and sweating and skin blood flow can no longer keep up.

40°C

Heat stroke

Above 40°C, cooling systems like sweating can stop working. This is a life-threatening emergency that needs immediate medical care.

Why Blacktown?

Hot surfaces like concrete, asphalt and dark roofs trap heat, while tree cover and green space are uneven. This builds the urban heat island effect.

Who is most at risk

  • Older adults: the body is slower to notice temperature changes.
  • Young children: bodies absorb heat faster and lose it faster.
  • Pregnant women: hormonal changes raise susceptibility.
  • Outdoor workers, athletes and people in low-income homes also face higher exposure.

Signs and symptoms

  • Mild: heat rash, painful muscle cramps.
  • Moderate (heat exhaustion): dizziness, nausea, weakness, fainting.
  • Severe (heat stroke): confusion or delirium, seizures, loss of consciousness. Call emergency services.

Our solution

A low-cost wearable that measures skin temperature and heart rate, sends the readings to your iPhone over Bluetooth, and tells you how much risk you are at.

1. Wear itTemperature and heart-rate sensors on the wrist
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2. BluetoothReadings sent to the phone
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3. AssessThe app works out the risk level
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4. AlertWarnings, advice and guardian alerts

Safe

Below 34°C, or below 120 BPM

Caution

34°C or above and 120 BPM or above

Danger

36°C or above and 130 BPM or above

We also added a Sport Mode to cut down unnecessary notifications during exercise.

Important: ThermoGuard is a student prototype, not a medical device. It does not diagnose heat stroke. It is designed to explore whether a wearable can flag risky heat exposure early so people act sooner. If someone shows signs of heat stroke, get emergency help immediately.

How we built it

From a fall-detection watch to a heat-stress monitor, with plenty of problem-solving along the way.

ResearchLearn about heat stress and early detection
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DesignPlan the watch and choose components
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BuildAssemble, connect and program
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Test & improveReal and manual readings, refine the app

Seeed Studio XIAO nRF52840

The brain. Reads the sensors, runs the heat-risk logic and sends data over Bluetooth.

MCP9808

Digital temperature sensor on the underside of the watch, measuring skin temperature.

MAX30102

Optical sensor that measures heart rate by detecting how skin changes with each pulse.

3.7 V LiPo battery

Rechargeable power so the watch works on its own.

The iPhone app

We first built Fall Guardian in Xcode with SwiftUI to detect falls. We then redesigned it into ThermoGuard, adding temperature and heart-rate monitoring, risk levels, health history, guardian settings and an emergency help button.

Challenges we solved

  • Apple Watch straps meant users would need special straps, so we designed a printable strap to lower costs.
  • The first base was one solid piece, so the electronics could not get readings. We redesigned it to hold the components.
  • A small gap kept the temperature sensor off the skin, so we investigated thermal silicone pads.
  • Invalid heart-rate readings showed us how much sensor position matters.
Earlier idea: our first concept was a physical Heat-Smart diorama of a new Sydney suburb like Marsden Park, showing how current building trends overheat suburbs. We chose the wearable because it could help individuals directly.

Our impact

Making personal heat monitoring more accessible, especially for older people, outdoor workers, athletes, students and anyone spending long periods in the heat.

Catch it early

Helps detect rising heat stress before it gets worse.

Practical and affordable

Built from low-cost parts so it can be used in real life.

Keeps people connected

Guardian alerts and location sharing help others step in when it matters.