1：Experimental Design and Method Selection:

The study involved fabricating a bottom-gate top-contact OTFT with a pyrene-SH functionalized layer to detect Hg2+ ions. The design rationale was based on the strong binding affinity of thiol groups to Hg2+ ions. Theoretical models included electrical characterization of OTFT performance and binding mechanisms.

2：Sample Selection and Data Sources:

Metal ion solutions (Hg2+, Ag2+, Cu2+, Mg2+, Mn2+, Ni2+, Zn2+, Pb2+, Ca2+, Co2+) were prepared in deionized water with concentrations from 1 mM to 0.01 μM. Water samples (tap, lake, seawater) were spiked with 25 μM Hg2+ ions for environmental testing.

3：01 μM. Water samples (tap, lake, seawater) were spiked with 25 μM Hg2+ ions for environmental testing. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Materials included Poly(methyl methacrylate) (PMMA), pentacene, pyrene-SH, chloride salts, dimethyl sulfoxide (DMSO), ethanol. Equipment included Keithley 4200 semiconductor analyzer, Agilent E4980A Precision LCR meter, VEECO Detak surface profilometer, atomic force microscopy (AFM, Bruker dimension icon), FEI Nova 200 scanning electron microscope for EDX, ICP-MS THERMO-ELEMENT XR, Sartorius Basic Meter PB-

4：Experimental Procedures and Operational Workflow:

Device fabrication involved cleaning ITO/glass substrate, spin-coating PMMA dielectric, evaporating pentacene layer, spin-coating Py-SH solution, and depositing gold contacts. Sensor characterization involved dropping 2 μL metal ion solutions on the channel, vacuum-drying, and measuring electrical properties. Environmental testing involved spiking water samples with Hg2+ and measuring responses.

5：Data Analysis Methods:

Data analysis included calculating dielectric constant from capacitance measurements, measuring film thickness and surface morphology, analyzing electrical characteristics (mobility, threshold voltage, on/off ratio), and using linear regression for sensitivity and limit of detection calculations.