## 2 Experimental Details  
Single-walled carbon nanotubes (SWCNTs) with a diameter of 1-2 nm from XFNANO Co. Ltd (Nanjing, China). were used in this experiment, as were multi-walled carbon nanotubes (MWCNTs) with a diameter of 30 nm to 50 nm. The purified CNTs were dispersed in a 1.5% mass fraction of sodium dodecyl sulfate (SDS) solution, and they were ultrasonically vibrated by an Ultrasonic cell grinder for 7 hours in a 20-degree water bath cooling to obtain a dispersed CNTs solution [20; 21]. In order to obtain two metal electrodes, we grew a 500 nm thick silicon dioxide film on a 500 \(\upmu\)m thick silicon wafer (Tebo Technology Co. Ltd., Harbin, China) by Plasma enhanced chemical vapor deposition (PECVD, ORION III, Trion Co. Ltd., Clearwater, FL, USA). Then, the pattern of the electrode was etched on the polymethyl methacrylate (PMMA) using electron beam direct-write lithography (EBL, CABL-9000 CSX, CRESTEC Co. Ltd., Tokyo, Japan) on the silicon oxide film. The electrode pattern is realized by two pieces of 120 * 120 pads connected by 180 \(\upmu\)m -long and 80 \(\upmu\)m wide lines. Thereafter, 100 nm thick metal Ni was sputtered by magnetron sputtering (Denton Co. Ltd., Moorestown, NJ, USA), and then the metal adhered to the PMMA was peeled off to obtain a desired electrode [22; 23]. The two metal electrodes were separated by a gap of 1 \(\upmu\)m. The structure diagram is shown in Figure 1.  
A sample injector (TopPette, Dragonmed Co. Ltd., Beijing, China) was used to draw 50 \(\upmu\)L of the dispersed SWCNTs solution onto the surface of the metal electrodes by drop coating, and allowed to naturally deposit at room temperature for 6 hours. The CNTs were naturally deposited on two metal electrodes, then immersed in deionized water for 5 minutes. After the dispersion was completely dissolved in water, it was taken out to obtain the desired sample. In order to avoid the influence of metallic CNTs or partially unstable CNT bundles on the test results, the electrical breakdown method can be used to remove them [24]. However, in the preliminary work of this experiment, we found that metallic CNTs or tube bundles were also damaged under the appropriate laser energy irradiation (less than the energy required for the connection), while the semiconducting CNTs were unaffected. Based on this phenomenon, we used this method to remove unwanted type of CNTs. A Nd:YLE solid state femtosecond laser device (Spitfire Ace-120F, Spectra-physics Inc., Vienna, Austria) was adopted in this experiment. The laser system delivers 120-fs-width pluses and operates at wavelengths of 800 nm. The repetition frequency utilized in the experiment was 1k Hz. The laser is perpendicular to the electrode and focuses on the electrode surface and the SWCNTs port area for a fixed point scan. Different from the precise spot welding by using the atomic force microscope (AFM) probe [25; 26; 27; 28; 29; 30], since the spot shape is a line, the entire edge of the electrode can be irradiated, which makes the method more efficient [31; 32]. Through multiple experiments, it was found that a suitable laser energy density for connecting SWCNTs to the Ni electrodes was about 13.810 m/cm\({}^{2}\), and that the irradiation duration was about 30 s. The positioning of the area to be processed and the area irradiated by the laser was achieved by means of a high-precision processing platform. The movement of the processing platform can be achieved through software programming (uFAB, NewPort Co. Ltd., Irvine, CA, USA). In this way, the laser can precisely irradiate the contact area of the electrode and the end of the CNT, thereby avoiding the influence on the area that does not need to be processed. All processing is carried out at room temperature and standard atmospheric pressure. At the same time, the surface topography of the samples before and after irradiation was observed using a field emission scanning electron microscope (FESEM, SU8010, Hitachi Co. Ltd., Tokyo, Japan).