A dual-mode portable biosensor based on photothermal-pyroelectric-electrochromic effects for versatile detection of enrofloxacin

Traditional photoelectrochemical (PEC) sensors are limited by bulky electrochemical workstations and high-energy light sources, thus limiting their practical applications. In this study, the photothermal effect of iron single-atom materials (Fe-PNC), pyroelectric effect of Yb-doped Bi₂S₃ (Yb-Bi₂S₃), and electrochromic effect of polyaniline (PANI) were innovatively combined to construct a dual-signal portable PEC sensing platform without the need of workstation. Specifically, we designed ITO electrode region: Yb-Bi₂S₃ nanorods were modified in the photothermal region, and PANI was electrodeposited in the discolored region. The Fe-PNC was introduced into the photothermal region through target-aptamer (Apt) sandwich strategy. Under the irradiation of 808 nm light, Fe-PNC converts light energy into heat energy, causing the temperature in the photothermal region to rise rapidly, thereby enhancing the pyroelectric effect of Yb-Bi₂S₃ and promoting carrier separation, so a large number of generated pyroelectric electrons migrate to the discolored region, and they trigger the PANI's reduction color-changing reaction (blue to green), thus achieving dual signal output of temperature and color. Based on this, we have successfully achieved highly sensitive and selective detection of enrofloxacin (ENR), which has the advantages of rapid response and intuitive reading. This design not only overcomes the problem of insufficient photogenerated carriers caused by the low energy of near-infrared (NIR) light, but more importantly, uses temperature and color changes to replace the traditional current signal detection, enabling the PEC sensor free of the electrochemical workstation. This research provides new ideas for the development of portable and low-cost PEC sensors.