Supplementary information

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1 Supplementary information Polyaniline anchored MWCNTs on fabric for high performance wearable ammonia sensor Debasis Maity 1, Ramasamy Thangavelu Rajendra Kumar 1,2* 1 DRDO -BU Center for Life Sciences, Bharathiar University, Coimbatore 64146, India. 2 Department of NanoScience and Technology, Bharathiar University, Coimbatore , Tamil Nadu, India. * Corresponding Author: rtrkumar@buc.edu.in Experimental setup for gas sensing measurement MFC 3 Input Chamber Water Sensor MFC 2 Ammonia solution Humidity probe Output MFC 1 Bubbler cylinder Open Valve H-341 Keysight 34972A Figure S-1. Schematic diagram of the Experimental setup for gas sensing measurement.

2 Gas sensing performance of sensor was investigated by measuring the change in resistance using two probe configurations upon exposure of alternative on 3 s and 45 s off cycle of ammonia vapors and carrier nitrogen respectively. The bubbler was used to generated vapors (ammonia, acetone, methanol, ethanol, xylene, isopropanol, Toluene, chloroform, benzene, and n-butanol). Water was used to control humidity inside the chamber. The vapors were generated by passing carrier nitrogen gas through bubbler and concentration was precisely controlled using programmable mass flow controller (MFC). SEM image: (a) (b) (c) (d) (e) (f) Figure-S2: SEM image of (a-b) Fabric, (c-d) F-MWCVNTs and (e-f)f-pani different magnification. The SEM image of untreated fabric and treated with spray coated MWCNTs and PANI different magnification was shown Figure-S2. The clean evidence of PANI coated fabric was observed.

3 TEM image of MWCNTs/PANI The TEM image of PANI/MWCNTs different magnification was provided in Figure S-3. It was conforming to the formation of a stable of the PANI/MWCNT composites. Figure-S3: TEM image of MWCNTs/PANI showing in different magnification XRD analysis (b) Raman analysis Figure S-4 (a) shows the X-ray diffraction pattern of F-MWCNTs, F-PANI, and F-MWCNTs/PANI. The diffraction peaks appeared at 2θ = 14.5, 16.2, 22.3, and 33.7 in both F-MWCNTs, F-PANI and F- MWCNTs/PANI those are due to cellulose of fabric (Polymorph I), matching with the previous study [34]. A small hump was observed at corresponding to (2) plane of MWCNTs (inset) for F-MWCNTs and F-MWCNTs/PANI sample. Although pyrolysis synthesized. MWCNTs have well define crystalline peaks at 26, 42, 54, and 78 correspond to the (2), (11), (4) and (11) planes, those peaks were not seen due to high-intensity background peaks of cellulose. There was no change in X-ray diffraction pattern

4 before and after PANI coating on fabric and F-MWCNTs. This means that nanomaterial alteration was left almost unchanged and maintained crystal structure and crystalline form of the fabrics. Figure S-4(b) shows the Raman spectra of F-MWCNTs and F-MWCNTs/PANI. The prominent peaks were observed around 135, 158 and 27 cm -1 corresponds to D, G, and G band of MWCNTs respectively [31-32]. Although the presence of fabric has not affected the vibration band of MWCNTs. PANI coating changes the D-band and G- band peaks position as well as enhance full width half maximum (FWHM) value. The D band of F- MWCNTs/PANI was shifted to 137 cm -1 due to the strong Π-Π electronic interaction between MWCNTs and PANI. The I D/I G ratio of F-MWCNTs was changed from.523 to.7 due to the presence of PANI and suppressed the tangential vibration of nanotubes on the surface of MWCNTs. The FWHM value of F- MWCNTs and F-MWCNTs/PANI for D band was 53.3 and cm -1 respectively. This enhancement may be due to the interaction of MWCNTs and PANI. Insensity (a.u) (a) F-MWCNTs/PANI F-PANI F-MWCNTs Insensity(a.u) PVA/MWCNTs on fabric MWCNTs (2) (degree) Intensity(a.u.) (b) 1355 D 1582 G F-MWCNTs/PANI F-MWCNTs 27 G' (degree) Raman Shift(cm -1 ) Figure S-4: (a) XRD analysis (b) Raman analysis of MWCNTs coated Fabric (F-MWCNTs and PANI/MWCNTs coated fabric (F-MWCNTs/PANI). Time-dependent Contact angle measurement The figure S-5 shows the hydrophobic nature of PANI-MWCNTs.

5 Figure S-5: Contact angle measurement as a function of time. Current-Voltage characteristics and Flexibility Measurements The I-V characteristics of F-MWCNTs, F-PANI, and F-MWCNTs/PANI were shown in Figure5(a). It can also be noticed from the I-V graph that PANI coated fabric and PANI coated MWCNTs on fabrics has higher resistance when compared to bare MWCNTs. The flexibility of F-MWCNTs, F-PANI, and F- MWCNTs/PANI were investigated by bending the fabric samples from 9 to 27 angle. Figure 5(b) shows a change in resistance of F-MWCNTs, F-PANI and F-MWCNTs/PANI as a function of bending angle. F-MWCNTs shows a drastic change in resistance on bending. It is interesting that F- MWCNTs/PANI shows very less change in resistance on bending in partial bending range 15 to 21 angle Change of resistance is low for F-MWCNTs/PANI that indicated that it can be used as a flexible wearable sensor. Figure S-6: (a) Current-Voltage characteristics (b) Flexibility test of F- MWCNTs, F-PANI and F-MWCNTs/PANI at different bending angles. Low-level ammonia response of F-MWCNTs/PANI The lower level (2 ppb to 5 ppm) sensor response of F-MWCNTs shown in Figure S-7.

6 16 14 F-MWCNTs/PANI (Ammonia) ppm 5 ppm S(%) ppm 4 2 ppm 2 2 ppb 3 ppb 4 ppb 5 ppb 6 ppb 7 ppb 8 ppb 9 ppb 1 ppm Times (S) Figure S-7: The response of F-MWCNTs/PANI towards different concentration of ammonia (low level 2 ppb to 5 ppm) Response and recovery time of F-MWCNTs and F-PANI under exposure of 1 ppm ammonia The response and recovery times of F-MWCTs was found to be 23 sec and 44 sec; where F-PANI was 18 sec and 4 sec respectively. (a) F-MWCNTs (1 ppm Ammonia) 8x1 4 7x1 4 (b) F-PANI (1 ppm Ammonia) 6x1 4 1x1 3 5x1 4 R 1 sccm R 4x1 4 1 sccm 23 Sec 44 Sec 3x1 4 2x Sec 4 Sec + NH 3 1x1 4 + NH Time (Sec) 5 Time (Sec) Figure S-8: Response and recovery time of (a) F-MWCNTs AND (b) F-PANI under 1 ppm ammonia.

7 Temperature-dependent ammonia sensing behavior of F-MWCNT/PANIs: Temperature-dependent ammonia sensing behaviors of F-MWCNTs/PANI at temperature 24 C, 32 C, 44 C, 55 C, 74 C and 86 C underexposure of 1 ppm ammonia S(%) Times (S) Figure S-9: Temperature-dependent ammonia sensing behaviors of F-MWCNTs/PANI at 24 C- 86 C under exposure of 1 ppm ammonia.