Portable Biosensing Platform Based On Conducting Polymer Decorated Optical Fiber For Bacteria As Well As Heavy Metal Sensing In Tap Water
Project Description :

The presence of water borne bacteria and heavy metals in tap water could be a potential human health risk and may lead to death in young children and adult with compromised immune system. the purpose of our research is to address these issues such a way that we can develop a common platform for the detection of water contamination for e.g. bacteria as well as heavy metals from tap water. the primary sensing mechanism is a suitably functionalized optical fiber. the fiber is of u-shaped, in order to increase the strength of the evanescent power, giving rise to a highly sensitive system. in brief, silica core optical fibers of 200μm core diameter (40cm long) were polished at terminal ends with emery paper. the cladding was removed from 2cm region in the centre. the optical fibers were bent using a butane flame to obtain a bent diameter of 1.5-1.6 mm. the u-bent fiber probes were cleaned using the method reported by chandra et al.2017 (1). distilled aniline was used as monomer and ammonium persulphate was used to initiate the polymerization. ammonium persulphate and aniline was mixed in 1:1 ratio in a test tube and the u-bend portion of the fiber probe was dipped in the solution. the polymerization occurs within 3-5 minutes and pani films were deposited on the sensor surface. all these steps have been done in real time to control deposition by monitoring the change in optical absorbance. the experimental setup consists of a broadband light source (450 -700 nm), light focusing optics and a portable fiber optic spectrometer. after the probe preparation, depending on the analyte for e.g. heavy metals or bacteria, polyaniline coated probes were functionalized with different receptors. for bacteria (e.coli, pseudomonas etc.) detection the sensor probe was functionalized with the bacteria specific antibodies whereas for heavy metal (lead, arsenic etc.) detection, heavy metals specific protein receptor was used to functionalize the sensor probe. in this way just changing the surface chemistry of the polyaniline coated sensor probe it can be made specific towards detection of different analyte using the same platform. as a proof of concept we have demonstrated (using laboratory based instrumentation) that as low as 20cfu/ml concentrations of e.coli and 1 picomolar concentration of lead ions are detectable using these systems. currently detection of all these contamination from tap water is in progress. to make it a hand-held biosensor, a u-shaped micro fluidic flow cell will be developed to encapsulate the u-bent optical fiber (typical diameter ~ 200µm). the cell will consist of a sample inlet and a sample outlet, and will be made of a suitable thermoplastic material. the receptor biomolecules will be immobilized on the sensor surface under flow conditions. the optical properties of polyaniline (pani) changes as the target analyte bind with the sensor probe. this leads to a change in the evanescent wave absorbance, which can be detected as a reduction in the light transmitted to an output photo- detector. the deliverable will be a marketable prototype of an optical fiber sensor integrated with microcontroller unit and flow cell system. automatic led stabilization as well as least pre-processing of minimal sample volume will be taken into account. the led display provides an automatic and visual readout mechanism to determine the concentration of analytes effectively. the main beneficiary will be the water industry, the residential as well as commercial sectors of economy. reference: 1. sutapa chandra, reshma bharadwaj, soumyo mukherji; label free ultrasensitive optical sensor decorated with polyaniline nanofibers: characterization and immunosensing application; sensors and actuators b 240 (2017) 443–450

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Project Details :
  • Date : Dec 11,2016
  • Innovator : Sutapa Chandra
  • Team Members : Sutapa Chandra,Arvind Dhawangale ,Prof. Soumyo Mukherji
  • Guide Name : Prof. Soumyo Mukherji
  • University : Indian Institutes of Technology Bombay
  • Submission Year : 2017
  • Category : Biological Sciences & Bioengineering
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