Capsule-based colorimetric temperature monitoring system for customizable cold chain management

•Temperature-responsive capsule with phase-change oil (PCO) layer was developed.•Phase transition of the PCO layer triggers the release of the encapsulated payload.•Temperature-responsive release enables simple colorimetric temperature monitoring.•Tuning of the PCO layer’s compositions can broaden the temperature range with precision.•Multiple temperature monitoring is also achieved by utilizing several sets of capsule.