Inkjet Printing of a Highly Loaded Palladium Ink for Integrated, Low-Cost pH Sensors

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• 作者：Yiheng Qin ; Arif U. Alam ; Matiar M. R. Howlader ; Nan-Xing Hu and M. Jamal Deen
• 刊名：Advanced Functional Materials
• 出版年：2016
• 出版时间：July 19, 2016
• 年：2016
• 卷：26
• 期：27
• 页码：4923-4933
• 全文大小：2080K
• ISSN：1616-3028

文摘

An inkjet printing process for depositing palladium (Pd) thin films from a highly loaded ink (>14 wt%) is reported. The viscosity and surface tension of a Pd-organic precursor solution is adjusted using toluene to form a printable and stable ink. A two-step thermolysis process is developed to convert the printed ink to continuous and uniform Pd films with good adhesion to different substrates. Using only one printing pass, a low electrical resistivity of 2.6 μΩ m of the Pd film is obtained. To demonstrate the electrochemical pH sensing application, the surfaces of the printed Pd films are oxidized for ion-to-electron transduction and the underlying layer is left for electron conduction. Then, solid-state reference electrodes are integrated beside the bifunctional Pd electrodes by inkjet printing. These potentiometric sensors have sensitivities of 60.6 ± 0.1 and 57 ± 0.6 mV pH⁻¹ on glass and polyimide substrates, and short response times of 11 and 6 s, respectively. Also, accurate pH values of real water samples are obtained by using the printed sensors with a low-cost multimeter. These results indicate that the facile and cost-effective inkjet printing and integration techniques may be applied in fabricating future electrochemical monitoring systems for environmental parameters and human health conditions.