Lts420

Optical cryomicroscope BX-51 (Olympus Corporation, Japan) was used to image the distribution of solution and ice crystals. A droplet (approx. 0.5 μl) of 50.4-mM sodium citrate buffer (mAb buffer without trehalose) was placed on an object plate and cooled in a temperature controlled cryostage LTS420 (Linkam Scientific Instruments, UK) using liquid nitrogen as a cooling medium. Samples were cooled to − 70°C at different rates between 0.5 and 5°C/min. Images were taken at − 70°C using a CCD camera after calibrating a ULWD 5×−50× objective (Olympus Corporation, Japan).

The DSC curves on a PerkinElmer DSC 6000 instrument under a nitrogen atmosphere at a heating and cooling rate of 10 K min⁻¹ was measured. The polycrystalline powder sample was placed in aluminum crucibles. It was performed temperature‐dependent SHG intensity on Ins 1 210 058, INSTEC Instruments using an unexpanded laser beam with low divergence (pulsed Nd: YAG at a wavelength of 1064 nm, 5 ns pulse duration, 1.6 MW peak power, 10 Hz repetition rate), and a Linkam LTS420 thermal stage was equipped to control the temperature. The laser was Vibrant 355 II, OPOTEK. The complex dielectric permittivity curves were measured on an automatic impedance Tonghui 2828 analyzer at the frequency of 1 MHz with the AC (Alternating Current) voltage of 1.0 V. For the dielectric measurements, the polycrystalline sample into powder and pressed it into a thin plate was first grounded. Then the conductive silver glue on both top and bottom plate surfaces as the electrodes of the sample sheet was deposited. Finally, silver conducting glue to stick the copper wire on it for connection with the six‐hole socket to form a capacitor was used.

The real-time resistance signals of the samples under different strains, temperatures, or humidities were recorded by Tektronix multimeter (DMM 4050) and Keithley multichannel source meter (DAQ6510). During test, electrical connections were made by conductive copper tapes. The heating and cooling cycles were carried out on a temperature-controlled platform (LTS420, Linkam). Prior to test, the sample was sealed on a glass plate with 3 M VHB tape to reduce the influence of humidity on its conductivity. ECG signals were measured using a Heal Force ECG recorder (PC-80B). EMG signals were recorded using the two-channel EMG sensor (ED0136/EDK0056, SICHIRAY). For adhesion and sensing applications, the hybrid ionic skins were attached to several body parts of a volunteer who participated in the experiment approved by the Institutional Biomedical Research Ethics Committee of Shanghai Institutes for Biological Sciences (No. 3011-19-03). All human participants gave written and informed consent before related experiments.

The POM observations were performed on the composites with a Leica microscope (DFC295, Leica Microsystems Corporation, Wetzlar, Germany) with a temperature controlled stage (LTS 420, Linkam Scientific Instruments, Tadworth, UK). The sample was first heating to 220 °C and maintained for 3 min, and then cooling down to 138 °C with the cooling rate of 50 °C/min maintained for 30 min. The crystal morphology of the sample can be observed at a constant temperature.

As a reservoir, we used a silicon wafer that has a circular hole with a 50 μm depth and 4 mm diameter. To reduce the meniscus of the water, we treated the O₂ plasma to minimize the meniscus before we dropped the water into the reservoir, and we casted 8CB (Sigma-Aldrich) on the water filled in the reservoir. The LC film thickness is ∼1.5 μm that varies with an amount of LC materials. The temperature control to induce the phase transition of LCs was performed on a heating stage (LINKAM LTS420) using a temperature controller (LINKAM TMS94).