Vernier Software and Technology
Vernier Software & Technology

Go Direct® Surface Temperature Sensor User Manual

Go Direct® Surface Temperature Sensor

Go Direct Surface Temperature is designed for use in situations in which low thermal mass or flexibility is required. Special features include an exposed thermistor that results in an extremely rapid response time.

Typical uses for Go Direct Surface Temperature include the following:

  • Skin temperature measurements
  • Human respiration studies
  • Specific heat experiments
  • Heat transfer experiments
  • Friction and energy studies

Note: Vernier products are designed for educational use. Our products are not designed nor are they recommended for any industrial, medical, or commercial process such as life support, patient diagnosis, control of a manufacturing process, or industrial testing of any kind.

What's Included

  • Go Direct Surface Temperature
  • Micro USB Cable

Compatible Software

Getting Started

Please see the following link for platform-specific connection information:

Bluetooth Connection

USB Connection

  1. Install Graphical Analysis 4 on your computer, Chromebook™, or mobile device. See for software availability.
  2. Charge your sensor for at least 2 hours before first use.
  3. Turn on your sensor by pressing the power button once. The Bluetooth® LED will blink red.
  4. Launch Graphical Analysis 4.
  5. Click or tap Sensor Data Collection.
  6. Click or tap your Go Direct sensor from the list of Discovered Wireless Devices. Your sensor's ID is located near the barcode on the sensor. The Bluetooth LED will blink green when it is successfully connected.
  7. Click or tap Done to enter data-collection mode.
  1. Install Graphical Analysis 4 on your computer or Chromebook. If using LabQuest 2, make sure LabQuest App is up to date. See for software availability or to update LabQuest App.
  2. Connect the sensor to the USB port.
  3. Launch Graphical Analysis 4 or turn on LabQuest 2. You are now ready to collect data.

Charging the Sensor

Connect Go Direct Surface Temperature to the included Micro USB Cable and any USB device for two hours.

You can also charge up to eight Go Direct Surface Temperature Sensors using our Go Direct Charge Station, sold separately (order code: GDX-CRG). An LED on each Go Direct Surface Temperature indicates charging status.


Blue LED on steady while sensor is connected to the Charging Cable or Charging Station.

Fully charged

Blue LED is off when charging is complete.

Providing Power

Turning on the sensor

Press button once. Red LED indicator flashes when unit is on.

Putting the sensor in sleep mode

Press and hold button for more than three seconds to put into sleep mode. Red LED indicator stops flashing when sleeping.

Connecting the Sensor

See the following link for up-to-date connection information:

Connecting via Bluetooth

Ready to connect Red LED flashes when sensor is awake and ready to connect via Bluetooth.
Connected Green LED flashes when sensor is connected via Bluetooth.

Connecting via USB

Connected and charging Blue and Green LED solid when sensor is connected to Graphical Analysis via USB and unit is charging. (Green LED is obscured by the blue one.)
Connected, fully charged Green LED solid when sensor is connected to Graphical Analysis via USB and the unit is fully charged.
Charging via USB,
connected via Bluetooth
Blue LED is solid and green LED is flashing, but the green flashing LED looks white because it is overwhelmed by the blue.

Identifying the Sensor

When two or more sensors are connected, the sensors can be identified by tapping or clicking Identify in Sensor Information.

Using the Product

Connect the sensor following the steps in the Getting Started section of this user manual.

Important: Go Direct Surface Temperature is for use in air and water only. For temperature measurements in harsher environments that require a more durable probe, we recommend our Go Direct Temperature (order code GDX‑TMP).


It should not be necessary to perform a calibration when using this sensor. It is calibrated before it ships.


Temperature range

–25°C to 125°C (–13°F to 275°F)

Maximum temperature that the sensor can tolerate without damage


Temperature sensor

20 kΩ NTC Thermistor


±0.5°C or better

Response time from 25°C to 100°C in water

5 seconds

Probe dimensions: probe length (handle plus body)

  • Handle: 7 cm high, 3.5 cm wide, 2 cm deep
  • Cable: 1 m
  • Submergible section: 7 cm

Care and Maintenance

Battery Information

Go Direct Surface Temperature contains a small lithium-ion battery in the handle. The system is designed to consume very little power and not put heavy demands on the battery. Although the battery is warranted for one year, the expected battery life should be several years. Replacement batteries are available from Vernier (order code: GDX-BAT-300).

Storage and Maintenance

To store Go Direct Surface Temperature for extended periods of time, put the device in sleep mode by holding the button down for at least three seconds. The red LED will stop flashing to show that the unit is in sleep mode. Over several months, the battery will discharge but will not be damaged. After such storage, charge the device for a few hours, and the unit will be ready to go.

Exposing the battery to temperatures over 35°C (95°F) will reduce its lifespan. If possible, store the device in an area that is not exposed to temperature extremes.

Water Resistance

The body of the Go Direct Surface Temperature Sensor is not water resistant and should never be immersed in water.

If water gets into the device, immediately power the unit down (press and hold the power button for more than three seconds). Disconnect the sensor and charging cable, and remove the battery. Allow the device to dry thoroughly before attempting to use the device again. Do not attempt to dry using an external heat source.

How the Sensor Works

This probe uses the 20 kΩ NTC Thermistor, which is a variable resistor. When the temperature increases, the resistance decreases non-linearly. The best-fit approximation to this nonlinear characteristic is the Steinhart-Hart equation. At 25°C, the resistance is approximately 4.3% per °C. The interface measures the resistance value, R, at a particular temperature and converts the resistance using the Steinhart-Hart equation:

T = [K0 + K1(ln 1000R) + K2(ln 1000R)3]-1 – 273.15

where T is temperature (°C), R is the measured resistance in kΩ, Ko =1.02119 × 10-3, K1 = 2.22468 × 10-4, and K2 = 1.33342 × 10-7. Our programs perform this conversion and provide readings in °C (or other units, if you load a different calibration).


First check that the sensor is responding: Connect the sensor and start the data‑collection program. Hold the tip of the sensor in your hand to warm it and check that the temperature changes.

For additional troubleshooting and FAQs, see

Repair Information

If you have followed the troubleshooting steps and are still having trouble with your Go Direct Surface Temperature, contact Vernier Technical Support at or call 888‑837‑6437. Support specialists will work with you to determine if the unit needs to be sent in for repair. At that time, a Return Merchandise Authorization (RMA) number will be issued and instructions will be communicated on how to return the unit for repair.


Item Order Code

Micro USB Cable


USB-C to Micro USB cable


Go Direct 300 mAh Replacement Battery



Vernier warrants this product to be free from defects in materials and workmanship for a period of five years from the date of shipment to the customer. This warranty does not cover damage to the product caused by abuse or improper use. This warranty covers educational institutions only.


When disposing of this electronic product, do not treat it as household waste. Its disposal is subject to regulations that vary by country and region. This item should be given to an applicable collection point for the recycling of electrical and electronic equipment. By ensuring that this product is disposed of correctly, you help prevent potential negative consequences on human health or on the environment. The recycling of materials will help to conserve natural resources. For more detailed information about recycling this product, contact your local city office or your disposal service.

Battery recycling information is available at

Do not puncture or expose the battery to excessive heat or flame.

The symbol, shown here, indicates that this product must not be disposed of in a standard waste container.

Contact Support

Fill out our online support form or call us toll-free at 1-888-837-6437.

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