Ni 9215

The main settings and procedures were the same as those in our previous study [9 (link)]. The participants were seated in front of a monitor (EV2450, EIZO) with headphones (HD280, Sennheiser). The right hand was used for the force generation task, and the left hand was used to respond to the auditory task by a keypress. In the force generation task, the force signals from the sensor (USL06-H5-50N-D-FZ, Tec Gihan) were transferred to a laptop computer at a sampling frequency of 200 Hz via an analog-to-digital converter (NI 9215, National Instruments). Data acquisition and stimulus presentation were carried out using MATLAB (MathWorks, Inc.) with the Data Acquisition Toolbox (MathWorks, Inc.) and Psychophysics Toolbox extensions [15 (link)–17 (link)].

The short-circuit current was measured by a SR570 Low-Noise Current Amplifier (Stanford Research Systems, USA). The output voltage was tested through the NI-9215 (National Instruments) under a load resistance of 100 MΩ.

To investigate the output performance of the TENG, an IVCL17-56 motor was used to periodically press and release the device. Short circuit current is measured by SR570 low-noise current amplifier (Stanford Research System, Sunnyvale, CA, USA) and the output voltage is measured by NI 9215 (National Instruments, Austin, TX, USA). Data were collected using LabVIEW programs (National Instruments, Austin, TX, USA).

To measure temperature above and below the glass window, we used thermocouples with tips of about 80 µm (Omega 5TC-TT-KI-40–1M). One thermocouple was placed below the glass window (i.e. on the brain surface) and permanently fixed to the cranial bone during the chronic implantation of the glass window. In n = 6 animals, temperature was daily monitored with an amplifier for thermocouples (NI-9215, 16bits, 100 Hz sampling rate, National Instruments) driven by a custom software (Labview 2013, National Instruments), revealing that 2–4 days were required to recover a temperature of ~37°C. Temperature was measured in the three imaging conditions, with a dry objective, a water immersion objective at room temperature and a heated water immersion objective. The same protocol was used for the experiments in awake mice with a reinforced thinned skull window over the barrel cortex (n = 3 mice). In these animals, the thermocouple was placed in the cortex superficial layers (II to IV) and not at the surface.

The EEG/EMG signals were amplified (gain ×1000) and filtered (EEG:1–300 Hz, EMG:10–300 Hz) using a DC/AC differential amplifier (AM-3000, AM systems, Sequim, WA, USA). The input was then received via an input module (NI-9215, National Instruments, Austin, TX, USA), digitized at a sampling rate of 1000 Hz using a data acquisition module (cDAQ-9171, National Instruments, Austin, TX, USA), and recorded using a custom-made LabVIEW program (National Instruments, Austin, TX, USA). We habituated the 24-hour EEG/EMG recordings more than three times; when REM sleep (see vigilance state assessment) was consistently observed, the experiment was initiated.

The EEG/EMG signals were amplified (gain 1000×) and filtered (EEG: 1–300 Hz, EMG: 10–300 Hz) using a DC/AC differential amplifier (AM-3000, AM Systems). The input was received via an input module (NI-9215, National Instruments), digitized at a sampling rate of 1000 Hz using a data acquisition module (cDAQ-9174, National Instruments), and recorded using a custom-made LabVIEW program (National Instruments). We habituated the 24 h EEG/EMG recordings more than three times, and REM sleep (see the vigilance state assessment) was often observed when we started the experiment. Three days before the control recordings on DOX-off day −1 (DOX-off day −4), the mice were placed in a soundproof box and connected to the EEG/EMG cable for the 24 h EEG/EMG recording of D2-DTA mice. They remained continuously tethered to the cable in the same soundproof box until day 11 of the DOX-off experiment. Cages and food were not changed during the stay in the soundproof box, except changing from DOX-containing chow to normal chow on Dox-off day 0.

The polarization P versus the electric field E curves were measured on the basis of the Sawyer-Tower method (14 ), where the polarization change of the system under periodic E is monitored through accumulated charges in a reference capacitor connected in series. An ac voltage of ~104 V at 1.0 Hz was applied to the PZT sample and reference capacitor of 10 μF in series. The time-dependent voltage in the reference capacitor was measured using a data acquisition device (NI, NI-9215) and converted into P(t), taking into account the sample dimensions and parasitic capacitance of connected cables. To measure the temperature (T) dependence of the P-E curve, the sample mounted on a sapphire substrate using insulating varnish (General Electronics, GE 7031) was placed in a cryostat for T < 300 K at vacuum and on a Peltier device for T > 300 K at atmospheric pressure. In the cryostat, the temperature of the sample was first lowered to 200 K without applying E (i.e., not poled) and increased after measurements at each temperature step. The derivative ∂P/∂E in Fig. 4B was obtained from the spline interpolation of the P-E curve.