The broad peak at around 3350 cm_1 is mainly originated from N-H vibration. For the fabrics that were coated with capsaicin-containing sol-gel solution, this peak was obviously higher than that of both the untreated wool fabric and the fabric coated with only sol-gel solution without containing any capsaicin. The peak at 1655 cm_1, the typical characteristic vibration of amide groups, also showed the same trend. This suggested that the coating layer contained moieties, which should be from the capsaicin molecules added.