Portable Sensor for Heavy Metal Detection in Water

• 17 Apr 2020

Why in News

Recently, the Centre for Nano and Soft Matter Sciences (CeNS) has developed a compact solid-state sensor to detect the heavy metal ions in water.

• It is a portable device which can help onsite detection in remote areas.

Key Points

• The compact solid-state sensor can detect the heavy metal ions like lead ions (Pb2+) down to 0.4 parts per billion (ppb).
• Mechanism:
  
  • A sensor film was prepared by forming a composite between manganese doped zinc sulfide quantum dots and reduced graphene oxide on a glass substrate.
  • These particular quantum dots are water-soluble and have high photoluminescence (~30%) quantum yield, making them suitable for luminescence-based sensing.
    
    • Luminescence is emission of light by certain materials when they are relatively cool. It may be seen in neon and fluorescent lamps.
  • These quantum dots can be excited with handheld UV (ultra-violet) light of 254 nm, thus making them portable even to remote areas.
    
    • Excitation, in physics, refers to the addition of a discrete amount of energy (called excitation energy) to a system—such as an atom, or a molecule—that results in its alteration, ordinarily from the condition of lowest energy (ground state) to one of higher energy (excited state).
  • If a drop of water containing heavy metal ions such as mercury (Hg), lead (Pb), cadmium (Cd), etc. are added to the composite film, the emission of the film extinguishes within seconds.
• The development of efficient and portable sensors for rapid onsite detection of heavy metal ions becomes important due to the health hazards associated with them.
  
  • Heavy metal ions pose severe potential threats to living beings (kidney damage, bone fractures, etc.).
  • They can be accumulated in the body easily and cannot be detoxified by any chemical or biological processes.
• This study demonstrates the easy detection of heavy metal ions in water. However, strategies are being developed to improve the selectivity of the detection.

Centre for Nano and Soft Matter Sciences

• It is an autonomous research institute under the Department of Science and Technology (DST), Government of India.
• DST provides core support to the Centre in the form of a grant-in-aid for conducting basic and applied research in nano and soft matter sciences.
• CeNS is located at Jalahalli, Bengaluru.
• It is being mentored by Nano-Mission of the Government of India.
• It is engaged in materials research at all relevant length scales.
  
  • The current activities are focussed on a variety of metal and semiconductor nanostructures, liquid crystals, gels, membranes and hybrid materials.
• The Centre was established in 1991 by an eminent liquid crystal scientist, Prof. S. Chandrasekhar, FRS. After years of expansion and name changes, in 2014, it became the Centre for Nano and Soft Matter Sciences (CeNS).

Nano Mission

• It was launched in 2007 as an umbrella capacity-building programme by the Government of India.
• It is being implemented by the Department of Science and Technology.
• Objectives:
  
  • Basic research promotion.
  • Infrastructure development.
  • Nano applications and technology development.
  • Human Resource development.
  • International collaborations.
• The Nano Mission has established national dialogues to promote R&D in the development of standards for nanotechnology and for laying down a National Regulatory Framework Road-Map for Nanotechnology (NRFR-Nanotech).

Source: PIB