Optical Biosensors Utilizing Polymer-Based Athermal Integrated Photonic Devices

In applications subject to temperature variations, developing temperature-insensitive photonic waveguide devices is crucial for ensuring the stability of wavelength-filtering devices. Here, we develop a polymer-based athermal photonic chip for optical biosensing. We adopt polydimethylsiloxane and poly(methyl methacrylate) as the waveguide materials and NOA61 as the substrate and propose an athermal optical demodulator photonic chip for physiological measurement on the basis of mutual compensation of the thermal optical effect and thermal expansion effect. The waveguide Bragg grating photonic sensor for measuring blood glucose and pressure has good temperature stability, and its temperature sensitivity can be reduced to -13.81-13.4 pm/°C. In the temperature range of 20-50 °C, the sensitivity of blood glucose measurement is 208.4 pm/(mg/mL), and the accuracy of blood glucose concentration measurement is 92.766% for 0-1.5 mg/mL; the sensitivity of the pressure measurement is 610 pm/kPa, and a pressure demodulation of 0-12 kPa can be achieved. The temperature sensor has a high temperature sensitivity of -207.8 pm/°C at 35-40 °C. Using cost-effective optical materials, we believe that this athermal design holds promise for overcoming the high temperature-dependent wavelength shift of photonic waveguide devices.