The present invention provides a composite material and a sensing platform unit comprising a self-healing polymer matrix and at least two conductive nanomaterials embedded therein. The polymer matrix has a multi-layer structure comprising a first layer comprising a network of a first nanomaterial, which resistance changes in response to a mechanical damage inflicted on the polymer matrix; and a second layer comprising a network of a second nanomaterial, configured to generate heat under applied voltage. The network of the first nanomaterial and the network of the second nanomaterial are electrically connected to a mutual control circuit which is configured to apply voltage to the second nanomaterial upon a change in resistance of the first nanomaterial. The sensing platform unit further comprises a third layer comprising a network of a third nanomaterial configured to detect at least one of pressure, strain, temperature, pH, humidity, and volatile organic compounds (VOCs).