Thermoelectric Response of Graphite/Na 1.4 Co 2 O 4 Thermocouple on Paper

Thermoelectric Response of Graphite/Na 1.4 Co 2 O 4 Thermocouple on Paper | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Thermoelectric Response of Graphite/Na 1.4 Co 2 O 4 Thermocouple on Paper Chandrababu Badampudi, Devang Anadkat, Shreya Dungani, Anil Pandya, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4842325/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 14 Feb, 2025 Read the published version in Discover Materials → Version 1 posted 19 You are reading this latest preprint version Abstract There is a demand for high-performance, environmentally friendly, mechanically robust, and economically viable thermoelectric generators (TEGs), with potential applications in electronic and energy conversion units as well as practical preparation techniques. We demonstrate the solid-state based synthesis and thermoelectric behavior of a Graphite/Na 1.4 Co 2 O 4 flexible thermocouple device that was printed on ordinary paper which acts as substrate. Four pair of TE legs fabricated with alternate graphite and Na 1.4 Co 2 O 4 traces, yielding of electrical conductivity, Seebeck coefficient and power factor for graphite traces 3333 Ω -1 m -1 , 26.78 µVK -1 & 2.39 µWm - ¹K -2 and Na 1.4 Co 2 O 4 traces 331 Ω -1 m -1 , 67.97 µVK -1 & 1.53 µWm - ¹K -2 , respectively are noteworthy. Our thermoelectric generator is cost effective and ecofriendly which provides good output performance. The thermocouple device's exhibits output voltage of 31.0 mV, this work provides insight into the potential for flexible thermoelectric heading beyond. Flexible thermocouple device resistance Seebeck coefficient paper substrate and graphite traces Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 INTRODUCTION Flexible thermoelectric materials are being studied worldwide due to their excellent lightweight properties for applications in wearable electronics, medical implants, wireless sensor networks and portable electronic equipment [1-4]. Conductive polymers have been recognized as the best flexible thermoelectric materials due to their ease of production and flexibility [5]. Compared to typical inorganic thermoelectric materials, organic materials are sufficiently flexible but exhibit a low carrier mobility and power output [6]. In recent years, transition metal oxides have received a lot of attention, specifically, a layered Cobalt (Co) oxide (Na x CoO 2 ), due to its remarkable transport properties [7-9]. Na x CoO 2 , a layered oxide, comprises of an insulating 'Na' layer intercalated between adjacent CoO 2 layers [10-14]. However, their application in flexible materials has been rarely reported. In particular, the thermoelectric power of cobalt-containing materials is very important because of the unique charge transfer mechanism [15]. The potential of Na x CoO 2 for thermoelectric applications has been studied by researchers and enhanced them by varying the Na content. Recent studies show that sodium-rich cobaltites with compositions ranging from 0.65 ≤ x ≤ 0.85 exhibit significantly higher thermoelectric power [8]. Oxide based thermoelectric materials with high adhesion, excellent durability, and soft texture were developed using an optimized preparation procedure. Na 1.4 Co 2 O 4 traces on flexible printing Xerox paper was reported to have Seebeck coefficient of 78 µVK -1 and more with in temperature ranges 30°C -250°C [16]. Graphite, on the other hand, is said to be naturally abundant, eco-friendly, and has a higher potential for application as a thermoelectric material due to its unique electrical and thermal characteristics [5, 16-18]. Mulla et al . (2021) highlighted graphite pencil as a promising choice for designing a flexible thermoelectric generator [19]. They also showed Seebeck coefficient values of 8 µVK -1 to 16 µVK -1 for graphite with grades ranging from HB to 6B on Xerox paper, respectively. In 2024, Dungani et al. proved HB graphite as a promising choice for designing thermoelectric generators, delivering an output voltage of 5.5 mV at a temperature gradient of 60 K [20]. Following them, our work revealed a simple and cost-effective approach for fabricating thermoelectric devices. The thermoelectric device was designed by simply painting on paper using Na 1.4 Co 2 O 4 bulks and HB graphite pencil. Furthermore, the thermoelectric characteristics of both materials have been investigated. This approach is not only easier to use than other methods for preparing devices, but it is also more ecologically friendly. This paper describes a straightforward manufacturing process for creating a low-voltage thermoelectric device with a working range of up to ΔT of 80 K, paving the way for the use of oxide and graphite-based thermoelectric materials in flexible devices. EXPERIMENTAL Preparation of bulk samples and flexible thermoelectric device Na 1.4 Co 2 O 4 powders were synthesized by a solid-state reaction method from the raw materials of NaNO 3 (Finar) and Co 3 O 4 (Ottokemi). Both materials were then taken in stoichiometric ratio and mixed in an agate mortar. The obtained mixture was then sintered at 750 °C for 5 h in air. The calcined powder was ground again in agate mortar. The fine, annealed powder was pressed into cylindrical pallets at a pressure of approximately 4 MPa. The prepared pallets were again sintered at 850 °C for 5 hours in a muffle furnace [5, 21]. The pallets were cooled naturally in a furnace after firing and further used for characterization. A simple (Natraj company) HB pencil is used to make traces on flexible Xerox paper by using the simple drawing method and is further used for characterization. In order to fabricate a thermoelectric device, we used normal Xerox paper as a substrate. Na 1.4 Co 2 O 4 pallet was traced on the paper to fabricate four legs of 3.2 cm length and 0.3 cm width. Then, to fabricate the other four legs in between the above-traced legs, HB pencil was used. Sufficient spacing is maintained between their alternate legs and the corresponding connections between their legs, as shown in Fig. 1. Characterizations The phase of Na 1.4 Co 2 O 4 and graphite traces on paper substrate was determined in an X-ray diffractometer (PANaltical, model X’Pert) with Cu Kα (1.54 Å) radiation. Electrical conductivity was measured in van der Pauw geometry, while the room temperature thermopower ( S ) was measured in home-made setup. We introduced the temperature difference (∆T ∼ 10 K) from different Peltier devices and kept K-type (100 µm diameter, OKAZAKI CO.) thermocouples on each side of the sample. They were further connected to the temperature controller (LakeShore CO., model 336) in order to monitor the temperature. The tungsten tip was mounted on each side to measure generated voltage and directly connected in Keithley 2450. Then, at room temperature, ∆V and ∆T were simultaneously measured [20, 22, 23]. The output performance of thermoelectric devices was measured by keeping half of the device in air and half on the hot plate as shown in Fig.1. To monitor the temperature, thermocouples were placed on each side and output voltage obtained by Keithley 2450. RESULTS AND DISCUSSION Figure 2 Shows the XRD patterns of the Xerox paper substrate used in device fabrication with graphite and Na 1.4 Co 2 O 4 . For graphite, all the peaks are aligned to the formation of a clear crystalline hexagonal structure with the (002) preferred orientation (JCPDS: 41-1484) Fig. 2 (a). The presence of CaCO 3 corresponds to planes of Xerox paper are evident, and no other impurities were detected [ 10 , 13 , 16 , 24 ]. The XRD of Na 1.4 Co 2 O 4 is shown in Fig. 2 (b). The pattern indicated that bulk Na1.4Co2O4 was in phase with (002) orientation at peak position (16.2°), which is consistent with the standard PDF card (JCPDS: 87–0274). However, in Na1.4Co2O4 flexible samples, a faint trace of Co3O4 was detected at location (19.01°), aside from the CaCO3 peaks of the Xerox paper substrate. This might be the result of Na + deintercalation between CoO2 octahedron layers during the tracing process, which damaged their layered structures. [ 17 , 25 , 26 ]. CoO 2 layer becomes vital in enhancing Seebeck coefficient [ 12 ]. From SEM micrograph, it is evident that Graphite and Na 1.4 Co 2 O 4 both have layered structures (Fig. 3 (a, b)). The cross-section of the flexible samples (Fig. 3 (c, d)) shows the thickness of the traces. The area on the cross-section, to the left side of the yellow dashed line was composed Xerox paper while the area on the right side of yellow dashed line contained Graphite (Fig. 3 (c)) and Na 1.4 Co 2 O 4 (Fig. 3 (d)) indicating that right side is the traced layer. The samples of the p-type Graphite and Na 1.4 Co 2 O 4 had thicknesses of 8 µm and 16 µm, respectively. The Graphite and Na 1.4 Co 2 O 4 layers were well combined with the paper substrate, its surface was relatively intact. It is observed that only after several trace trials, this kind of uniformity of Graphite and Na 1.4 Co 2 O 4 traces would be achieved that enhances the conductivity. The electrical resistance of the TE materials is also important for their overall performance. The room temperature resistance of graphite and Na 1.4 Co 2 O 4 traces were measured in Vander Pauw geometry and are plotted at room temperature (Fig. 4 (a), (b), (c) and (d)). There is a considerable change in the resistance of Graphite and Na 1.4 Co 2 O 4 [ 11 ] from 37.53 Ω to 189 Ω, yields to difference in the values of thermopower as 26.78 µV/K and 67.97 µV/K as observed, respectively. The Seebeck coefficient of Graphite and Na 1.4 Co 2 O 4 traces as function of temperature gradient is shown in Fig. 4 (c, d). Since the thermopower values are positive which show the majority hole carriers [ 13 , 27 ]. At room temperature, electrical and thermal properties of Graphite and Na 1.4 Co 2 O 4 traces shown in Table 1 . Further, with the use of the experimental arrangement showed in an illustration Fig. (1), the output performance of the device was carried out as a function of temperature gradient up (Δ T ) to 85 K. The resultant output voltage (Δ V ) of thermocouples fabricated on Xerox paper is 31.0 mV as shown in Fig. (5). Table 1 Electrical and Thermal properties of traces at room temperature. Name of the trace Seebeck S (µV/K) Resistance R (Ω) Thickness t (µm) Resistivity ρ (Ωm) Conductivity σ (Ω −1 m −1 ) Power Factor ( S 2 σ ) (µWm − 1 K − 2 ) Graphite 26.78 37.53 8 0.3×10 − 3 3333 2.39 Na 1.4 Co 2 O 4 67.97 189 16 3.024×10 − 3 331 1.53 CONCLUSION The output voltage of the thermocouple is good, and the protocol of simplicity of manufacturing, eco-friendliness, and cost effectiveness is achieved for producing thermocouple device. Our thermocouple is made up of Na 1.4 Co 2 O 4 and graphite having thermopower of 67.97 µV/K and 26.78 µV/K which is also higher compare to AgSbO 3 and other similar materials [ 28 ]. It produces about 31 mV of output voltage till the temperature gradient range of 85 K, and it can be further used to sense the temperature of different material. Flexible thermoelectric devices hold promise for revolutionizing various industries by enabling the efficient conversion of waste heat into usable electricity. Ongoing research developments are driving the advancement of these devices, making them more practical, efficient and versatile for a wide range of applications. An adequate amount of voltage is produced from flexible thermocouple device. Industrial electronics, health monitoring systems, and self-powered wireless gadgets are a few examples of applications where thermoelectric generators can be used and which demand a highly reliable solution [ 29 – 32 ]. A wearable wireless pulse oximeter, implanted medical devices (IMDS) that monitor cardiac activity, and electronic and microelectronic devices that operate on very low input powers [ 29 , 31 – 35 ], where our flexible thermoelectric conversion devices are anticipated. Declarations There are no conflicts of interest to declare. Data availability The authors confirm that the data and findings of this study are available in the article. Row data that supports the results of this study is available from the corresponding authors, upon reasonable request. Acknowledgements This research was supported by the Department of Physics, School of Energy Technology, Pandit Deendayal Energy University. We thank to Solar Research and Development Centre, Pandit Deendayal Energy University for structural measurements. Author Contributions Conceptualization: A.V.S.; Sample preparation and measurements: C.B., D.A., S.D., A.P.; Original draft preparation: C.B., D.A., A.P.; Data analysis and Methodology: A.V.S, C.B., D.A., A.P.; Writing – review & editing: C.B., D.A., A.P., A.V.S.; Supervision: A.V.S References Rafique, S., Badiei, N., Burton, M. R., Gonzalez-Feijoo, J. E., Carnie, M. J., Tarat, A., & Li, L. ACS Omega, 6(7), 5019-5026 (2021) Kong, D., Zhu, W., Guo, Z., & Deng, Y. Energy , 175 , 292-299 (2019) Marin, G., Tynell, T., & Karppinen, M. J. Vac. Sci. Technol .A , 37 (2). (2019). Karunanithy, M., G. Prabhavathi, A. Hameedha Beevi, B. H. Ibraheem, K. Kaviyarasu, S. Nivetha, N. Punithavelan, A. Ayeshamariam, and M. Jayachandran. J. Nanosci. Nanotechnol. 18, no. 10, 6680-6707 (2018) Yang, Shiqi, Pengfei Qiu, Lidong Chen, and Xun Shi. Small science 1, no. 7, 2100005 (2021) Liang, J., Wang, T., Qiu, P., Yang, S., Ming, C., Chen, H., ... & Chen, L. Energy Environ. Sci. 12 (10), 2983-2990 (2019). 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4842325","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":350100830,"identity":"47edfd8b-7072-482c-abf5-267663fbb829","order_by":0,"name":"Chandrababu Badampudi","email":"","orcid":"","institution":"Pandit Deendayal Energy University","correspondingAuthor":false,"prefix":"","firstName":"Chandrababu","middleName":"","lastName":"Badampudi","suffix":""},{"id":350100831,"identity":"1821fdc4-ba58-4e0f-aae2-87c41256c7cb","order_by":1,"name":"Devang Anadkat","email":"","orcid":"","institution":"Pandit Deendayal Energy University","correspondingAuthor":false,"prefix":"","firstName":"Devang","middleName":"","lastName":"Anadkat","suffix":""},{"id":350100833,"identity":"e22e0ffe-485f-4c6b-a873-576ddd9b7629","order_by":2,"name":"Shreya Dungani","email":"","orcid":"","institution":"Pandit Deendayal Energy University","correspondingAuthor":false,"prefix":"","firstName":"Shreya","middleName":"","lastName":"Dungani","suffix":""},{"id":350100836,"identity":"4d085824-7f4e-4e59-aa44-2192c0fc47a5","order_by":3,"name":"Anil Pandya","email":"","orcid":"","institution":"Pandit Deendayal Energy University","correspondingAuthor":false,"prefix":"","firstName":"Anil","middleName":"","lastName":"Pandya","suffix":""},{"id":350100844,"identity":"21c2cef8-f545-48db-8816-3c2f40f9e243","order_by":4,"name":"Anup V. Sanchela","email":"data:image/png;base64,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","orcid":"","institution":"Pandit Deendayal Energy University","correspondingAuthor":true,"prefix":"","firstName":"Anup","middleName":"V.","lastName":"Sanchela","suffix":""}],"badges":[],"createdAt":"2024-08-01 12:55:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4842325/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4842325/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s43939-025-00206-w","type":"published","date":"2025-02-14T15:58:03+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":64091260,"identity":"88b51f4b-ce16-48b9-b350-c6a4b55010a9","added_by":"auto","created_at":"2024-09-06 14:41:49","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":75818,"visible":true,"origin":"","legend":"\u003cp\u003ePhotographic image of Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e based thermoelectric generator with individual traces of Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. Homemade setup for measuring output voltage of thermoelectric generator.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4842325/v1/ed1c3125d119641519825acd.jpg"},{"id":64091263,"identity":"286faaee-aa38-4d51-9983-e29d531118ca","added_by":"auto","created_at":"2024-09-06 14:41:49","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":40215,"visible":true,"origin":"","legend":"\u003cp\u003eXRD pattern of \u003cstrong\u003e(a)\u003c/strong\u003e Graphite trace, \u003cstrong\u003e(b)\u003c/strong\u003e Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e trace.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4842325/v1/27f5d7dce37087c374787d2d.jpg"},{"id":64091264,"identity":"477fd9f4-7364-44e1-9653-07d8f513bd90","added_by":"auto","created_at":"2024-09-06 14:41:49","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":113825,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e and \u003cstrong\u003e(c)\u003c/strong\u003e Seebeck coefficient measurement from the slope of D\u003cem\u003eV\u003c/em\u003e vs. D\u003cem\u003eT\u003c/em\u003e plot \u003cstrong\u003e(b)\u003c/strong\u003e and \u003cstrong\u003e(d)\u003c/strong\u003e Electrical resistance of samples 10×10 mm\u003csup\u003e2\u003c/sup\u003e size of Graphite traces, and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4842325/v1/bd9757aa2fa771f111a1bb5b.jpg"},{"id":64091261,"identity":"746cdf8b-ed36-4ac9-817e-69b69caa80ce","added_by":"auto","created_at":"2024-09-06 14:41:49","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":54163,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) \u003c/strong\u003eand\u003cstrong\u003e (b)\u003c/strong\u003e Surface morphology of Graphite trace \u0026amp; Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e trace, Inset show the layers in both traces, \u003cstrong\u003e(c)\u003c/strong\u003e and \u003cstrong\u003e(d)\u003c/strong\u003e cross- section image for find out the thickness.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4842325/v1/667db85cc29d393e1224c847.jpg"},{"id":64091265,"identity":"312c8dbb-39b7-491e-9e51-042b495a0833","added_by":"auto","created_at":"2024-09-06 14:41:49","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":20874,"visible":true,"origin":"","legend":"\u003cp\u003eOutput voltage of thermoelectric device as a function of temperature difference.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4842325/v1/11000c9281a6c374e55f8302.jpg"},{"id":76488244,"identity":"d71e0c46-77b9-4e2e-af7b-030214accd12","added_by":"auto","created_at":"2025-02-17 16:13:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":825357,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4842325/v1/3fb291cf-88b0-4f95-8e08-47b1c581621c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Thermoelectric Response of Graphite/Na 1.4 Co 2 O 4 Thermocouple on Paper","fulltext":[{"header":"INTRODUCTION ","content":"\u003cp\u003eFlexible thermoelectric materials are being studied worldwide due to their excellent lightweight properties for applications in wearable electronics, medical implants, wireless sensor networks and portable electronic equipment [1-4]. Conductive polymers have been recognized as the best flexible thermoelectric materials due to their ease of production and flexibility [5]. Compared to typical inorganic thermoelectric materials, organic materials are sufficiently flexible but exhibit a low carrier mobility and power output [6]. In recent years, transition metal oxides have received a lot of attention, specifically, a layered Cobalt (Co) oxide (Na\u003csub\u003ex\u003c/sub\u003eCoO\u003csub\u003e2\u003c/sub\u003e), due to its remarkable transport properties [7-9]. Na\u003csub\u003ex\u003c/sub\u003eCoO\u003csub\u003e2\u003c/sub\u003e, a layered oxide, comprises of an insulating \u0026apos;Na\u0026apos; layer intercalated between adjacent CoO\u003csub\u003e2\u003c/sub\u003e layers [10-14]. However, their application in flexible materials has been rarely reported. In particular, the thermoelectric power of cobalt-containing materials is very important because of the unique charge transfer mechanism [15]. The potential of Na\u003csub\u003ex\u003c/sub\u003eCoO\u003csub\u003e2\u003c/sub\u003e for thermoelectric applications has been studied by researchers and enhanced them by varying the Na content. Recent studies show that sodium-rich cobaltites with compositions ranging from 0.65 \u0026le; x \u0026le; 0.85 exhibit significantly higher thermoelectric power [8]. Oxide based thermoelectric materials with high adhesion, excellent durability, and soft texture were developed using an optimized preparation procedure. Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces on flexible printing Xerox paper was reported to have Seebeck coefficient of 78 \u0026micro;VK\u003csup\u003e-1\u003c/sup\u003e and more with in temperature ranges 30\u0026deg;C -250\u0026deg;C [16].\u003c/p\u003e\n\u003cp\u003eGraphite, on the other hand, is said to be naturally abundant, eco-friendly, and has a higher potential for application as a thermoelectric material due to its unique electrical and thermal characteristics [5, 16-18]. Mulla \u003cem\u003eet al\u003c/em\u003e. (2021) highlighted graphite pencil as a promising choice for designing a flexible thermoelectric generator [19]. They also showed Seebeck coefficient values of 8 \u0026micro;VK\u003csup\u003e-1\u003c/sup\u003e to 16 \u0026micro;VK\u003csup\u003e-1\u003c/sup\u003e for graphite with grades ranging from HB to 6B on Xerox paper, respectively. In 2024, Dungani et al. proved HB graphite as a promising choice for designing thermoelectric generators, delivering an output voltage of 5.5 mV at a temperature gradient of 60 K [20].\u003c/p\u003e\n\u003cp\u003eFollowing them, our work revealed a simple and cost-effective approach for fabricating thermoelectric devices. The thermoelectric device was designed by simply painting on paper using Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e bulks and HB graphite pencil. Furthermore, the thermoelectric characteristics of both materials have been investigated. This approach is not only easier to use than other methods for preparing devices, but it is also more ecologically friendly. This paper describes a straightforward manufacturing process for creating a low-voltage thermoelectric device with a working range of up to \u0026Delta;T of 80 K, paving the way for the use of oxide and graphite-based thermoelectric materials in flexible devices.\u003c/p\u003e"},{"header":"EXPERIMENTAL","content":"\u003cp\u003e\u003cstrong\u003ePreparation of bulk samples and flexible thermoelectric device\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNa\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e powders were synthesized by a solid-state reaction method from the raw materials of NaNO\u003csub\u003e3\u003c/sub\u003e (Finar) and Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (Ottokemi). Both materials were then taken in stoichiometric ratio and mixed in an agate mortar. The obtained mixture was then sintered at 750 °C for 5 h in air. The calcined powder was ground again in agate mortar. The fine, annealed powder was pressed into cylindrical pallets at a pressure of approximately 4 MPa. The prepared pallets were again sintered at 850 °C for 5 hours in a muffle furnace [5, 21]. The pallets were cooled naturally in a furnace after firing and further used for characterization. A simple (Natraj company) HB pencil is used to make traces on flexible Xerox paper by using the simple drawing method and is further used for characterization. In order to fabricate a thermoelectric device, we used normal Xerox paper as a substrate. Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e pallet was traced on the paper to fabricate four legs of 3.2 cm length and 0.3 cm width. Then, to fabricate the other four legs in between the above-traced legs, HB pencil was used. Sufficient spacing is maintained between their alternate legs and the corresponding connections between their legs, as shown in Fig. 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacterizations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe phase of Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and graphite traces on paper substrate was determined in an X-ray diffractometer (PANaltical, model X’Pert) with Cu Kα (1.54 Å) radiation. Electrical conductivity was measured in van der Pauw geometry, while the room temperature thermopower (\u003cem\u003eS\u003c/em\u003e) was measured in home-made setup. We introduced the temperature difference (∆T ∼ 10 K) from different Peltier devices and kept K-type (100 µm diameter, OKAZAKI CO.) thermocouples on each side of the sample. They were further connected to the temperature controller (LakeShore CO., model 336) in order to monitor the temperature. The tungsten tip was mounted on each side to measure generated voltage and directly connected in Keithley 2450. Then, at room temperature, ∆V and ∆T were simultaneously measured [20, 22, 23]. The output performance of thermoelectric devices was measured by keeping half of the device in air and half on the hot plate as shown in Fig.1. To monitor the temperature, thermocouples were placed on each side and output voltage obtained by Keithley 2450.\u003c/p\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e2\u003c/span\u003e Shows the XRD patterns of the Xerox paper substrate used in device fabrication with graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. For graphite, all the peaks are aligned to the formation of a clear crystalline hexagonal structure with the (002) preferred orientation (JCPDS: 41-1484) Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a). The presence of CaCO\u003csub\u003e3\u003c/sub\u003e corresponds to planes of Xerox paper are evident, and no other impurities were detected [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The XRD of Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e2\u003c/span\u003e (b). The pattern indicated that bulk Na1.4Co2O4 was in phase with (002) orientation at peak position (16.2\u0026deg;), which is consistent with the standard PDF card (JCPDS: 87\u0026ndash;0274). However, in Na1.4Co2O4 flexible samples, a faint trace of Co3O4 was detected at location (19.01\u0026deg;), aside from the CaCO3 peaks of the Xerox paper substrate. This might be the result of Na\u0026thinsp;+\u0026thinsp;deintercalation between CoO2 octahedron layers during the tracing process, which damaged their layered structures. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. CoO\u003csub\u003e2\u003c/sub\u003e layer becomes vital in enhancing Seebeck coefficient [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. From SEM micrograph, it is evident that Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e both have layered structures (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a, b)). The cross-section of the flexible samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003e(c, d)) shows the thickness of the traces. The area on the cross-section, to the left side of the yellow dashed line was composed Xerox paper while the area on the right side of yellow dashed line contained Graphite (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003e(c)) and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003e(d)) indicating that right side is the traced layer. The samples of the p-type Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e had thicknesses of 8 \u0026micro;m and 16 \u0026micro;m, respectively. The Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e layers were well combined with the paper substrate, its surface was relatively intact. It is observed that only after several trace trials, this kind of uniformity of Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces would be achieved that enhances the conductivity. The electrical resistance of the TE materials is also important for their overall performance. The room temperature resistance of graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces were measured in Vander Pauw geometry and are plotted at room temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a), (b), (c) and (d)). There is a considerable change in the resistance of Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] from 37.53 Ω to 189 Ω, yields to difference in the values of thermopower as 26.78 \u0026micro;V/K and 67.97 \u0026micro;V/K as observed, respectively. The Seebeck coefficient of Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces as function of temperature gradient is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e4\u003c/span\u003e(c, d). Since the thermopower values are positive which show the majority hole carriers [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. At room temperature, electrical and thermal properties of Graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces shown in Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Further, with the use of the experimental arrangement showed in an illustration Fig.\u0026nbsp;(1), the output performance of the device was carried out as a function of temperature gradient up (Δ\u003cem\u003eT\u003c/em\u003e) to 85 K. The resultant output voltage (Δ\u003cem\u003eV\u003c/em\u003e) of thermocouples fabricated on Xerox paper is 31.0 mV as shown in Fig.\u0026nbsp;(5).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eElectrical and Thermal properties of traces at room temperature.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026times;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eName of the trace\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSeebeck\u003c/p\u003e \u003cp\u003e\u003cem\u003eS\u003c/em\u003e (\u0026micro;V/K)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eResistance\u003c/p\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e (Ω)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eThickness \u003cem\u003et\u003c/em\u003e\u003c/p\u003e \u003cp\u003e(\u0026micro;m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eResistivity\u003cem\u003eρ\u003c/em\u003e\u003c/p\u003e \u003cp\u003e(Ωm)\u003c/p\u003e\u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eConductivity\u003cem\u003eσ\u003c/em\u003e\u003c/p\u003e \u003cp\u003e(Ω\u003csup\u003e\u0026minus;1\u003c/sup\u003em\u003csup\u003e\u0026minus;1\u003c/sup\u003e)\u003c/p\u003e\u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePower Factor (\u003cem\u003eS\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u003cem\u003eσ\u003c/em\u003e)\u003c/p\u003e \u003cp\u003e(\u0026micro;Wm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eK\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGraphite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e26.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c5\"\u003e \u003cp\u003e0.3\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3333\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2.39\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNa\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e67.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e189\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c5\"\u003e \u003cp\u003e3.024\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e331\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe output voltage of the thermocouple is good, and the protocol of simplicity of manufacturing, eco-friendliness, and cost effectiveness is achieved for producing thermocouple device. Our thermocouple is made up of Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and graphite having thermopower of 67.97 \u0026micro;V/K and 26.78 \u0026micro;V/K which is also higher compare to AgSbO\u003csub\u003e3\u003c/sub\u003e and other similar materials [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. It produces about 31 mV of output voltage till the temperature gradient range of 85 K, and it can be further used to sense the temperature of different material. Flexible thermoelectric devices hold promise for revolutionizing various industries by enabling the efficient conversion of waste heat into usable electricity. Ongoing research developments are driving the advancement of these devices, making them more practical, efficient and versatile for a wide range of applications. An adequate amount of voltage is produced from flexible thermocouple device. Industrial electronics, health monitoring systems, and self-powered wireless gadgets are a few examples of applications where thermoelectric generators can be used and which demand a highly reliable solution [\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. A wearable wireless pulse oximeter, implanted medical devices (IMDS) that monitor cardiac activity, and electronic and microelectronic devices that operate on very low input powers [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan additionalcitationids=\"CR32 CR33 CR34\" citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], where our flexible thermoelectric conversion devices are anticipated.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThere are no conflicts of interest to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors confirm that the data and findings of this study are available in the article. Row data that supports the results of this study is available from the corresponding authors, upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis research was supported by the Department of Physics, School of Energy Technology, Pandit Deendayal Energy University. We thank to Solar Research and Development Centre, Pandit Deendayal Energy University for structural measurements.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConceptualization: A.V.S.; Sample preparation and measurements: C.B., D.A., S.D., A.P.; Original draft preparation: C.B., D.A., A.P.; Data analysis and Methodology: A.V.S, C.B., D.A., A.P.; Writing – review \u0026amp; editing: C.B., D.A., A.P., A.V.S.; Supervision: A.V.S\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eRafique, S., Badiei, N., Burton, M. R., Gonzalez-Feijoo, J. E., Carnie, M. J., Tarat, A., \u0026amp; Li, L. 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Pulse oximeter fully powered by human body heat.\u003c/li\u003e\n\u003cli\u003eTorfs, T., Leonov, V., Yazicioglu, R.F., Merken, P., Van Hoof, C., Vullers, R.J. and Gyselinckx, B., \u003cem\u003eIEEE Sens. J.,\u003c/em\u003e pp. 1269-1272 (2008).\u003c/li\u003e\n\u003cli\u003ePatidar, S., \u003cem\u003eInt. J. Res. Appl. Sci. Eng. Technol\u003c/em\u003e, \u003cem\u003e6\u003c/em\u003e(5), pp.1992-1996 (2018).\u003c/li\u003e\n\u003cli\u003eDilhac, J.M., Month\u0026eacute;ard, R., Bafleur, M., Boitier, V., Durand-Est\u0026egrave;be, P. and Tounsi, P., \u003cem\u003eJ. Electron. Mater.\u003c/em\u003e, \u003cem\u003e43\u003c/em\u003e, pp.2444-2451 (2014).\u003c/li\u003e\n\u003cli\u003eIezzi, B., Ankireddy, K., Twiddy, J., Losego, M.D. and Jur, J.S., \u003cem\u003eAppl. Energy\u003c/em\u003e, \u003cem\u003e208\u003c/em\u003e, pp.758-765 (2017).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"dime","sideBox":"Learn more about [Discover Materials](https://www.springer.com/journal/43939)","snPcode":"","submissionUrl":"","title":"Discover Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Flexible thermocouple device, resistance, Seebeck coefficient, paper substrate and graphite traces","lastPublishedDoi":"10.21203/rs.3.rs-4842325/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4842325/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThere is a demand for high-performance, environmentally friendly, mechanically robust, and economically viable thermoelectric generators (TEGs), with potential applications in electronic and energy conversion units as well as practical preparation techniques. We demonstrate the solid-state based synthesis and thermoelectric behavior of a Graphite/Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e flexible thermocouple device that was printed on ordinary paper which acts as substrate. Four pair of TE legs fabricated with alternate graphite and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces, yielding of electrical conductivity, Seebeck coefficient and power factor for graphite traces 3333 Ω\u003csup\u003e-1\u003c/sup\u003em\u003csup\u003e-1\u003c/sup\u003e, 26.78 \u0026micro;VK\u003csup\u003e-1\u003c/sup\u003e \u0026amp; 2.39 \u0026micro;Wm\u003csup\u003e-\u003c/sup\u003e\u0026sup1;K\u003csup\u003e-2\u003c/sup\u003e and Na\u003csub\u003e1.4\u003c/sub\u003eCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e traces 331 Ω\u003csup\u003e-1\u003c/sup\u003em\u003csup\u003e-1\u003c/sup\u003e, 67.97 \u0026micro;VK\u003csup\u003e-1\u003c/sup\u003e \u0026amp; 1.53 \u0026micro;Wm\u003csup\u003e-\u003c/sup\u003e\u0026sup1;K\u003csup\u003e-2\u003c/sup\u003e, respectively are noteworthy. Our thermoelectric generator is cost effective and ecofriendly which provides good output performance. The thermocouple device's exhibits output voltage of 31.0 mV, this work provides insight into the potential for flexible thermoelectric heading beyond.\u003c/p\u003e","manuscriptTitle":"Thermoelectric Response of Graphite/Na 1.4 Co 2 O 4 Thermocouple on Paper","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-06 14:41:44","doi":"10.21203/rs.3.rs-4842325/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-24T08:14:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-18T05:58:44+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-12T19:50:48+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-12T08:28:04+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-09T05:53:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-09T05:33:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"113997511402895499902464003870700583424","date":"2024-09-09T01:32:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-09T01:22:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"166842080781647602560692662127691865036","date":"2024-09-09T01:11:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"306205211174407463309767294877508749779","date":"2024-09-07T18:01:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"170014751498918129965976502469187895918","date":"2024-09-07T11:53:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"127560465927538416624785808023823683780","date":"2024-09-05T15:17:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"11352933053266749898838318840309491834","date":"2024-09-05T13:08:48+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-04T09:23:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"54448652116866341578479458678391472220","date":"2024-08-24T11:46:12+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-22T13:50:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-08-12T06:46:36+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-09T12:10:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Materials","date":"2024-08-01T12:53:41+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"dime","sideBox":"Learn more about [Discover Materials](https://www.springer.com/journal/43939)","snPcode":"","submissionUrl":"","title":"Discover Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"50da177c-610d-4cf0-a510-d1241fb53067","owner":[],"postedDate":"September 6th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-02-17T16:10:43+00:00","versionOfRecord":{"articleIdentity":"rs-4842325","link":"https://doi.org/10.1007/s43939-025-00206-w","journal":{"identity":"discover-materials","isVorOnly":false,"title":"Discover Materials"},"publishedOn":"2025-02-14 15:58:03","publishedOnDateReadable":"February 14th, 2025"},"versionCreatedAt":"2024-09-06 14:41:44","video":"","vorDoi":"10.1007/s43939-025-00206-w","vorDoiUrl":"https://doi.org/10.1007/s43939-025-00206-w","workflowStages":[]},"version":"v1","identity":"rs-4842325","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4842325","identity":"rs-4842325","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}