Biomed story songThermal paper in ECG recorders
Thermal Side Up
Why an ECG prints a blank strip: the thermal paper roll is loaded upside down.
A biomed story song from our shop-floor series. Diagrams are simplified to tell the story; this is not a service procedure, so always follow the manufacturer's instructions and your facility's policy.
The story behind it: Thermal paper in ECG recorders
Most electrocardiograph recorders print with heat, not ink. The paper has a heat-sensitive coating on one side only, and the print head darkens that coating where it touches. If the roll is loaded with the coated side facing away from the head, the machine runs normally but the strip comes out blank.
A quick check is the scratch test from the song: drag a fingernail across the paper. The coated side shows a grey or dark mark from the friction heat. That side goes toward the print head.
Reviewed November 1, 2026. General information, not a service procedure: follow the manufacturer's instructions and your facility's policy.
Put the steps in order
Tap step 1 of 4.