Alpha300m

The quality of graphene was analyzed through Raman spectroscopy (Alpha300M, Witec). The electrical properties of the single SBT, SIC, glucose/insulin sensor, and AS were evaluated using a Keithley 4200A‐SCS and vacuum probe station system. The real‐time output signals of ANC components were measured using a digital phosphor oscilloscope (DPO3052, Tektronix).

First, DNA or Cu²⁺-DNA/MoS₂/SiO₂/Si samples were investigated and compared with a control sample (MoS₂/SiO₂/Si). Then, the DNA or Cu²⁺-DNA/MoS₂/SiO₂/Si samples with doxorubicin were measured using PL/Raman spectroscopy (Alpha300M +, WITec). Here, TMD bulk flakes with similar thicknesses (~32 nm) were selected to avoid the thickness effect. Raman spectroscopy with an excitation wavelength of 532 nm was used, where the laser beam size was approximately 0.7–0.9 μm, and the instrumental spectral resolution was less than 0.9 cm⁻¹. An integration time of 5 seconds and a spectrometer with 1800 grooves/mm were used. For the KPFM measurement, a platinum/iridium (Pt/Ir) coated Si tip was used and the tip was calibrated on a HOPG surface. First, we calculated the work function of the KPFM tip (W_tip − W_HOPG = ΔV_{CPD_HOPG}) using the well-known work function of the HOPG (W_HOPG = 4.6 eV) and the contact potential difference between tip and HOPG (ΔV_{CPD_HOPG} = 324 meV). We then found the work function of the TMD layers with the calculated W_tip (4.92 eV) value and the measured ΔV_{CPD_TMD} between KPFM tip and TMD surface (W_tip − W_TMD = ΔV_{CPD_TMD}).

To analyze the structural characteristics and strain distribution of our nanopillar devices, we used a field-emission SEM (JSM-7600F, JEOL), AFM (Park XE 15, Park systems), and Raman spectroscopy (Alpha300 M+ , WITec). The electron acceleration voltage in SEM was set to 10 kV. AFM measurement was performed on nanopillar sample in tapping mode. The scan size, resolution, and speed were set to 10 × 10 μm², 512 × 512 pixel² and 0.5 Hz, respectively. For Raman spectroscopy characterization, a 532-nm excitation laser was used along with a 100× objective lens. During the measurement, additional care was taken to keep the laser power low enough to avoid any heating effect. The strain-shift coefficient of 65.4 cm^–1/%^{26 (link)} was used to estimate the maximum strain of 1.3% in our nanopillar device. The theoretical limit of spatial resolution (i.e., diffraction-limited spatial resolution) of our Raman system can be calculated using Abbe’s diffraction limit: $\mathrm{Spatial}\mathrm{resolution}=\frac{0.61\lambda }{\mathrm{NA}},$ where λ is the wavelength of the excitation laser, and NA is the numerical aperture of the microscope objective. In our experiment, we used a 532-nm laser with a 0.90/100x objective lens, resulting in a spatial resolution limit of 361 nm.

Raman measurements
were performed using a confocal Raman microscope (Alpha 300 M+, WITec,
Germany) with a laser wavelength of 532 nm. The SERS performance of
the surface was evaluated by using rhodamine 6G (R6G, Sigma-Aldrich)
as the probe molecule. Spectra were recorded by focusing the laser
beam with a power of 1.5 mW on the sample surface with a 100×
microscope objective (NA = 0.95) at an integration time of 0.5 s.
The SERS activity of the nanostructures was evaluated by calculating
the analytical enhancement factor (AEF) with the following equation^{35 (link)} Here, C_SERS (1
nM) and C_Raman (1 mM) are the concentrations
of the R6G placed on the reference (Si wafer) and the nanostructured
surface, respectively. I_SERS and I_Raman are the corresponding signal intensity
at the peak of 1362 cm^–1 in the measured spectra
of R6G.
To collect the SERS spectra of various bacteria, suspensions
containing 10³ cfu/mL bacteria (in Muller–Hinton
broth) were washed three times to remove the impurities, followed
by dispersing in PBS. Consequently, a 100 μL of bacterial solution
in PBS was retrieved and spotted on the nanostructures and left to
dry for 40 min. SERS spectra were recorded with a laser power of 10
mW and integration time of 0.5 s.

Large-area graphene films and single graphene crystals transferred onto SiO₂/Si substrates were characterized by Raman microscopy (WITec GmbH, Model: Alpha300M+) with an excitation laser wavelength of 532 nm. A laser power of ca. 2 mW was used for all measurements. The backscattered laser light containing the Raman bands from 1200 to 3000 cm⁻¹ was collected by a CCD camera (Andor, Model number: DV401A-BV-352) integrated with the WITec system. The characteristic Raman signature collected from a p-doped Si wafer at 520.7 cm⁻¹ was employed as standard calibration. Raman mapping was conducted by raster scan, where the step size of the laser spot moving over a selected area is 1 µm, and the exposure time of 0.4 s was taken at each point of the mapping. In the maps, the intensity of D and 2D bands were normalized to the G band intensity. Corresponding statistics were extracted from the maps.

Graphene G peaks were measured by Raman spectroscopy (Alpha300 M+, WITec) with a 100× objective and 1800 g/mm grating. Laser wavelength was 532 nm. Before measurement, laser power was adjusted to low level to avoid heating effect. Lorentz fitting was applied to determine peak position and FWHM.

Ln-DNA or Co-DNA-doped TMD samples were investigated and compared with a control sample (undoped TMD) by PL/Raman spectroscopy (Alpha300 M+, WITec). Here, TMD bulk flakes with similar thickness (~38 nm for MoS₂ and ~33 nm for WSe₂) were selected through AFM analysis in order to avoid the thickness effect. Raman spectroscopy with an excitation wavelength of 532 nm was used; the laser beam size was approximately 0.7 ~ 0.9 μm, and the instrumental spectral resolution was less than 0.9 cm⁻¹. An integration time of 5 seconds and a spectrometer with 1800 grooves/mm was employed for the test.