Agriculture biosensors types
What is biosensor? A biosensor is an analytical device which converts a biological reaction into an electrical signal. Biosensors can be defined as analytical devices which contain a combination of biological detecting elements like sensor system and a transducer. The applications of these Biosensors mostly include checking ecological pollution control, in agriculture field as well as food industries. The major features of biosensors are stability, cost, sensitivity, and reproducibility. The aim of a biosensor is to create either discrete or continuous electronic signals which are proportional to a single analyte or a related group of analytes.
In the agricultural industries, the quality of a product is evaluated through periodic chemical and microbiological analyses which are expensive, slow, need well-trained operators and in some cases, need steps of extraction or pretreatment, increasing the time of analysis. Biosensors can give rapid, non-destructive and affordable methods for the quality monitoring of a product. Biosensors decrease assay time and cost or increase product safety.
Biosensors have been adapted to detect analytes in on-line systems. Biosensors have the potential to make an analytical revolution to resolve the problems in the agricultural and the food industries. Now, let us get into details of agriculture biosensors types and their principles in the farming sector.
Working of Biosensors
The preferred biological material like enzyme is chosen for conventional methods like physical or membrane entrapment and noncovalent or covalent binding. The chosen biological material is in contact with the transducer. To create a bound analyte through the analyte binds to the biological material this produces the electrical response to be measured. In some cases, the analyte changed to a product and have some probability to connect with the release of heat, gases like oxygen, electrons or hydrogen ions.
- Linearity should be high for the detection of high substrate concentration.
- Sensitivity importance of electrode response per substrate concentration.
- Selectivity chemical interference must be minimized for obtaining correct Result.
- Response time necessary for having 95% of the response.
Agriculture biosensors types for environmental monitoring
Stricter regulations and a greater public awareness of environmental issues carry requirements to monitor an ever-wider range of analytes in air, soil, and water with greater accuracy. Increased public concerns over the safety of the environment also foster a need to monitor pathogens in field and stream. With greater pressure to recycle water, minimize the use of antibacterial agents and to keep quality discharges, manufacturers in a wide variety of industries are seeking technologies to rapidly identify contamination problems at the source. Meanwhile, operators are looking to have the costs of increasingly complex monitoring regimes. Biosensors capable of detecting an organism quickly will be very important in the environmental monitoring of the pathogens.
The durability, sensitivity and low cost of signal transducers and the rising availability of enzymes, antibodies and genetically engineered microorganisms that related with environmental pollutants have contributed to the recent interest in applying biosensors to environmental monitoring.
Principle of Biosensor
Immobilization of biological material
The biological components are suitably immobilized on the transducer surface. Enzymes are generally immobilized by glutaraldehyde onto a porous sheet-like lens tissue paper or nylon net fabric and the enzyme membrane thus produced are affixed to the transducer.
Surface treatment to the transducer
The transducer surface can be treated with 3-aminopropyl triethoxysilane. The biological components may now covalently link to this cross-linked silane via the reactive amino group remains free. This process yields non-reproducible results and often causes a large reduction in the activity of the biological components.
Interaction of analyte with biological material
The biological component interacts particularly to the analyte, which produces a physical change close to the transducer surface. This physical change may be heat released or absorbed by the reaction, production of electrical potential due to change distribution of the electrons, movement of electrons due to redox reactions, the light produced or absorbed by the reaction, modify in the mass of biological components as a result of the reaction.
Conversion of biological signal
The transducer detects the signal and converts into the electrical signals.
Amplification of signal
This signal is necessarily small and is amplified by the amplifier before it is fed into the microprocessor. The signal is then processed and interpreted and is displayed into the appropriate units.
Agriculture biosensors types
There are many types of Biosensors based on the sensor devices and the biological materials and some of them are discussed below.
It is a very simple device. It measures the measurement of electronic current, ionic or by conductance changes conceded by bio-electrodes. The sensor substrate generally contains three electrodes; a reference electrode, an active electrode, and a sink electrode. An auxiliary electrode (also known as a counter electrode) may be present as an ion source. The target analyte is involved in the reaction that takes place on the active electrode surface, and the ions produced to make a potential which is subtracted from that of the reference electrode to give a signal.
Whole cell biosensor
In this type of biosensor whole cell or organelles use as a biological component. The cells are very cheaper, have a longer active lifetime, and are less sensitive to inhibition, pH, and temperature variations than enzymes.
The use of amperometric biosensors in signal transduction has verified to be the most widely reported using an electrochemical approach. Both “one-shot” (disposable) sensors and on-line (multi-measurement) devices are commercially obtainable, monitoring a wide range of target analytes. In contrast to potentiometric devices, the principle operation of amperometric biosensors is defined by a constant potential useful between a working and a reference electrode. The functional potential results in redox reactions, causing a net current to flow. The magnitude of this current is proportional to the concentration of electroactive species there in test solution & both cathodic (reducing) and anodic (oxidizing) reactions can be monitored amperometrically. Most of the amperometric biosensors explained use enzymes as the biorecognition element. Normally, oxidase and dehydrogenase enzymes have been the most frequently exploited catalysts used for these biosensor formats.
This form of biosensor provides a logarithmic reply by means of a high energetic range. These biosensors are frequently complete by monitor creating the electrode prototypes lying on a synthetic substrate, covered by a performing polymer with some enzyme is connected. The biosensors comprise two electrodes which are enormously responsive and strong.
All types of biosensors normally occupy least sample preparation since the biological detecting component is extremely choosy used for the analyte troubled. By the changes of physical and electrochemical the signal will be generated by in the layer of conducting polymer suitable to modifying happening at the outside of the biosensor.
It detects how much light is produced or absorbed through the biochemical reaction. A most capable biosensor is luminescence biosensor for the detection of bacteria in food and clinical samples. Bacteria are also used as a biosensor it gets fluoresces in the presence of specific pollutants which they like to eat and detect the oil spills area.
Read: Urban Agriculture Techniques.
Biosensors in Agriculture
Agriculture includes the production of crops and the rearing of livestock producing different products which are used in daily life. These elements have always been disposed to damage in the form of pests and diseases causing a loss in the profits. Hence, a way of increasing profits would be to decrease the loss of crops and livestock by such natural threats. With the advancement in bioterrorism, the need for biosecurity becomes necessary. Also, the need for biosecurity is necessary when agricultural produce or any living object is to be transported across international borders. Biosensors can play a major role in this field as they provide rapid and specific detection compared to the older techniques.
A concentration of herbicides, pesticides and heavy metals in agricultural lands is increasing and this is a matter of concern. Biosensors can be used to compute the levels of pesticides, herbicide, and heavy metals in the soil and groundwater. Biosensors can be used to forecast the possible occurrence of soil disease, which has not been feasible with the existing technology. The biological diagnosis of soil using biosensor means opening the approach to reliable prevention and decontamination of soil disease at an earlier stage.
The basic principle of soil diagnosis with the biosensor is to approximate the relative activity of “good microbes” and “bad microbes” in the soil on the source of quantitative measurement of differential oxygen consumption in the respiration of two types of soil microorganisms. The measurement proceeds during two sensors impregnated with “good microbes” and “bad microbes”, respectively, are immersed in a suspension of the soil sample in buffer solution.
By comparing two data it can be possible to quantitatively decide which microbe favors the soil. It is feasible, therefore, to predict whether or not soil disease is prepared to break out in the tested soil beforehand. It is to be emphasized that the biosensor offers an innovative system of diagnosing soil condition based not on experience but on numerical data. Nitrate biosensor has been developed for the detection of the quantity of nitrate present in the soil.
Enzyme biosensors based on the inhibition of cholinesterases have been used to identify traces of organophosphates and carbamates from pesticides. Selective and sensitive microbial sensors for the quantity of ammonia and methane have been studied. However, the commercially obtainable biosensors for wastewater quality manage are biological oxygen demand (BOD) analyzers based on micro-organisms like the bacteria Rhodococcus erythropolis immobilized in collagen or polyacrylamide.
Applications of biosensors
- Biosensors have a very wide range of applications that aim to develop the quality of life.
- This range covers their use for environmental monitoring, disease recognition, food safety, defense, drug discovery and many more.
- Biosensors can be used as platforms for monitoring food traceability, quality, safety, and nutritional value.
- These applications fall into the group of ‘single shot’ analysis tools, i.e. where cost-effective and disposable sensing platforms are required for the application.
- An application such as pollution monitoring requires a biosensor to function from a few hours to several days.
That’s all folks about agriculture biosensors types used in the agriculture sector.