5.4.9 SensorsSantos and Tercjak [486] developed an optical sensor platform composed of CNC and 40-(hexyloxy)-4-biphenylcarbonitrile.The obtained material showed the synergistic effect of properties of both compounds: the intensestructural coloration of photonic cellulose and thermal and conductive properties of CNC. Film optical properties were found to be switchable with the temperature during heating/cooling cycles. Then, the created film is both thermal and electrical responsive in photonic.Low-cost piezoelectric devices are used as fast diagnostic tools for several diseases detection, but some inconveniences, like unspecific antigen recognition, poor molecular probe adsorption, and the need for sample dilution, may limit their use in routine diagnostics. Pirich andde Freitas [487] coated piezoelectric sensors with thin films of BC-CNC to improve the attachment of monoclonal immunoglobulin G (IgGNS1) and to favor specific detection of nonstructural protein 1 (NS1) of dengue fever. The complete sensor was able to detect the NS1protein in serum in the range of 0.0110 μg/mL.