1558-1748 (c) 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2019.2947607, IEEE Sensors Journal > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < 1 Abstract— Iron ion, an essential element for environmental as well as biological systems, has to be present in a controlled manner. Presence of excess iron and also the deficiency of iron ions in environmental (groundwater) and biological systems (blood serum and parts of the plant) is an enduring concern. Here we have developed a nano-sensor (FeNSOR) using a neutral micelle (TX- 100) duly sensitized by porphyrin. We have also fabricated an instrument called “FeNSOR Device” (Iron sensor) based on the developed nano-sensor using a digital Pi-camera with associated hardware and software. The device works on the principle of fluorescence spectrophotometry. The efficacy of the nano-sensor and the device for the detection and estimation of iron ions in groundwater as well as in human blood serum sub-molar range. Having minimum interference with other ions the limit of detection (LOD) and the standard deviation of the mean have found to be 0.07 M and 0.016 M, respectively. The developed device is easy to handle and has a greater detectability and repeatability than the commercially available ones. Index Terms— Nano-sensor, Spectroscopy, Iron ions, Image analysis, Raspberry Pi I. INTRODUCTION RON is so important that life without it cannot be imagined. It is the second most important trace element for biological as well as environmental systems. It is one of the essential element to survive, grow and remain healthy for every living being. Iron exists either in Fe 2+ and Fe 3+ oxidation states and can readily combine with oxygen and sulphur-containing compounds to form oxides, hydroxides, carbonates, and sulphides. It has been accounted that water with low levels of iron, turns to insoluble ferric (Fe 3+ ) iron from soluble ferrous or bivalent form (Fe 2+ ) due to oxidation [1]. Previous studies depicted that the insoluble ferric ions create toxicity in groundwater [2, 3] as well as in biological systems [4-6]. Water may contain different quantities of iron ions depending on geographical location. However, in treated water, the cut-off Animesh Halder is with Technical Research Centre, S.N.Bose National Centre for Basic Sciences and perusing PhD from Department of Applied Optics and Photonics, University of Calcutta, Salt Lake, Kolkata, India (e-mail: animesh.snbncbs@ gmail.com). Deep Shikha is with Technical Research Centre, S.N.Bose National Centre for Basic Sciences, Salt Lake, Kolkata, India (e-mail: deepshikha.labh@gmail.com). Aniruddha Adhikari is with Department of Chemical, Biological and Macromolecular Sciences, S.N.Bose National Centre for Basic Sciences, Salt Lake, Kolkata, India (e-mail: aniruddha.biosc@gmail.com). Ria Ghosh is with Technical Research Centre, S.N.Bose National Centre for Basic Sciences, Salt Lake, Kolkata, India (e-mail: ria.ghosh1995@gmail.com). iron ions concentration is often below the official treatment goal of 0.3 ppm, defined by the World Health Organization (WHO) [7]. Disorders in iron metabolism [8] may lead to a broad spectrum of diseases with diverse clinical manifestations, ranging from anemia [9] to iron overload [10-12], and neurodegenerative diseases [13]. Not only in animals, iron is one of the essential nutrients for plants also. It has been well reported that plant growth depends upon the rate of uptake and translocation of metal nutrients [14, 15]. Change in concentration of iron ion disrupts the functioning of plants, which results in the imbalance of environmental and biological systems. Therefore, detection and estimation of iron ion concentration are important to investigate the cause of diseases in plants and human beings along with controlling environmental hazards. In contemporary time, different spectrophotometry techniques like atomic absorption spectrometry [16], inductively coupled plasma mass spectrometry [17, 18], electrochemistry [18, 19] are extensively used in the detection of iron ions in biological sample but limited by their high setup cost and complexity in the sample preparation. For testing the concentration of iron ions in water some chemical methods dependent upon photometer and color comparator which are low cost and portable. Moreover, the use of such devices are restricted due to treatment of the sample with reductant, surfactant, and/or acid agents to prepare a homogeneous solution, thus inapplicable to living samples. Recently, different types of fluorescence spectrophotometry [20] being low cost and easy method for detection of metal ions are used, but their studies are limited due to low LOD (limit of detection ) values [21]. In this paper, we have proposed a low-cost portable instrument based on self-developed nano-sensor (FeNSOR) as shown in Scheme 1. The nano-sensor is developed on a neutral micelle (Triton X-100) duly sensitized by porphyrin [22]. The sensitized micelle upon interaction with iron ions quenches the porphyrin fluorescence of the micelle. We have utilized the Soumendra Singh is with Center for Astroparticle Physics and Space Science, Bose Institute and perusing PhD from Department of Chemical, Biological and Macromolecular Sciences, S.N.Bose National Centre for Basic Sciences, Salt Lake, Kolkata, India (e-mail: soumendras@gmail.com). Tapan Adhikari is the principal scientist in Indian Institute of Soil Science, Nabibagh, Berasia Road, Bhopal, Madhyapradesh, India (email: tapan_12000@rediffmail.com) Samir Kumar Pal is with Technical Research Centre, S.N.Bose National Centre for Basic Sciences and Department of Chemical, Biological and Macromolecular Sciences, S.N.Bose National Centre for Basic Sciences, Salt Lake, Kolkata, India (e-mail: skpal@ bose.res.in). (Corresponding author: Samir Kumar Pal) Development of A Nano-sensor (FeNSOR) Based Device for Estimation of Iron ions in Biological and Environmental Samples Animesh Halder, Deep Shikha, Aniruddha Adhikari, Ria Ghosh, Soumendra Singh, Tapan Adhikari, and Samir Kumar Pal I