2.3. NIR Actuation of the Polymeric Bilayer and the Magnetic Field Manipulation

An 808 nm laser (the light spot is around 2 mm × 4 mm) was chosen to control the deflection of the polymeric bilayer actuator. The light density was recorded by an intensity meter (THORLAB PM 200D, Newton, NJ, USA). The real-time temperature mapping of the millirobot upon NIR light irradiation was measured by an infrared camera (Optris PI400, Ferdinand, Germany, test range: −20 °C~100 °C). The highest temperature was obtained by a portable infrared camera (Testo 865, Schwarzwald, Germany, test range: −20 °C~280 °C). The magnetic flux density was measured by a digital Gauss/Tesla meter (Beijing, China), and a linear motor (LinMot E1100, Spreitenbach, Swiss) was employed to control the position of the magnet.