Flir ets320

Before the temperature measurement, the emissivity of each sample was measured. A black tape (HB-250, OPTEX Co., Ltd., Shiga, Japan) with a known emissivity of 0.95 was used as a reference for the emissivity measurement. The paper and the black tape were heated to 50 °C by a temperature controller (SBX-303, Sakaguchi E.H VOC Corp., Tokyo, Japan). Then, a digital thermometer (MT-309, MotherTool Co. Ltd., Ueda, Japan) with a thermal couple sensor (TP-11, MotherTool Co. Ltd., Ueda, Japan) was used to ensure that both the paper and the black tape achieved the same temperature. By adjusting the temperature of the paper measured with an infrared thermal camera (FLIR ETS320, FLIR Systems. Inc., Wilsonville, USA), according to the reference temperature of the black tape, the emissivity of the paper was measured. In the temperature measurement, a solar simulator (AM1.5G, wavelength: 350–1800 nm, HAL-320W, Asahi Spectra Co., Ltd., Tokyo, Japan) was used as the light source. The power intensity was measured by a thermal sensor power meter (PM160T, Thorlabs, Inc., New Jersey, USA). The samples were placed on an acrylic plate, which had a hole (Φ 70 mm) in the middle. After emissivity calibration of each sample, the surface temperature changes of the samples during illumination of solar simulator were recorded by the infrared thermal camera.

Three by three arrays of graphite droplets were printed into micropillars with diameters of ~2.0 mm and heights of ~1.5 mm on a copper foil substrate to form a sensor area of ~1 cm by 1 cm. Rings of hBN were then deposited around each micropillar and the structure was infiltrated with PDMS to form the final device. The stress–strain curve and electromechanical properties of the resultant sensors were tested using a compression tester (Instron 3366). The two pieces of copper foils sandwiching the printed graphite micropillars were connected a two-probe multimeter. The electrical resistance was monitored while a compressive force with a ramp rate of 5 N min⁻¹, up to a maximum of 40 N was applied to the sensor. To check the repeatability and stability of the sensor signals, the measurements were performed after every 10 compression cycles up to 30 cycles.
The thermal properties of the sensors were characterised using a thermal camera (FLIR ETS320). A lever system using a tweezer and a support was used to apply a force onto the sensor area. This was done to ensure that the sensor area would be unobstructed for the camera to record its temperature. Weights were placed onto the middle of the tweezer to apply pressures equivalent to 1 kPa and 25 kPa onto the sensor area. For each loading and unloading step, the temperature was recorded until a saturation temperature was reached.

The SEM images were taken by the field emission scanning electron microscope (Hitachi S-4700 with EDS). The XPS spectra were obtained by Kratos Axis Supra x-ray photoelectron spectrometer, allowing to determine the elemental composition of the top ~ 10 nm of the sample surface. The XRD patterns of functional nanocomposites were obtained using the Rigaku SmartLab theta-theta diffractometer. The FTIR spectra were recorded using Hyperion 1000 with Tensor 27 spectrometer. The thermal images were taken with an infrared (IR) camera (FLIR ETS320). The performance of the drug-release patch was characterized with a Ultraviolet-visible (UV-vis) spectrometer (VWR UV-1600PC).