6 - BIOSENSORS Flashcards
- An analytical device that detects changes in biological processes (biological element or material like enzymes, tissues, microorganisms, cells, acids, etc) and converts them into an electrical signal
- A combination of a biological sensing element and a transducer, which converts the data into electrical signals
- There will be an electronic circuit which consists of a signal conditioning unit, a processor or microcontroller and a display unit
Biosensors
- A chemical process of converting the enzymes into corresponding electrical signals (usually current) with the help of a transducer
Electroenzymatic approach
Oxidation acts as a catalyst and alters the pH of the biological material. The change in pH will directly affect the current carrying capacity of the enzyme, which is once again, in direct relation to the enzyme being measured. Output of the transducer i.e. the current, is a direct representation of the enzyme being measured. The current is generally converted into voltage so that it can be properly analyzed and represented
Commonly used biological response is the oxidation of the enzyme
The combination of a biological sensitive element and a transducer will convert the biological material into a corresponding ?
electrical signal
Depending on the type of enzyme, the output of the transducer will be either ?
current or voltage
well and good (output)
voltage
it should be converted into equivalent voltage before proceeding further (output)
current
The output voltage signal is usually very low in amplitude and superimposed on a high frequency noise signal. So, the signal is amplified (using an ?) and then passed through a
Op-Amp based Amplifier, Low Pass RC Filter
- Process of amplifying and filtering the signal
- Output is an analog signal that is equivalent to the biological quantity being measured
Signal Processing Unit or a Signal Conditioning Unit
- Is a voltage, current, or physical quantity that continuously and infinitely varies in accordance with some time-varying parameter
- Examples are radio waves, television or sound waves
Analog Signal
Consists of a test strip, which collects a small sample of blood to analyze the glucose levels. This particular sensor implements the Electroenzymatic approach i.e. oxidation of glucose
Glucometer
- Used in the analysis or the method of transduction implemented
- Commonly used biological elements or bio-recognition elements are DNA, enzymes, antibodies, microorganisms, tissues, cell receptors etc
Biological Element
Type of physiochemical resulting from the sensing event
Transducting Method
- Also known as Acoustic Biosensors
- Based on the principle of sound vibrations i.e. acoustics
- When a mechanical force is applied on a piezoelectric biosensor, they produce an electrical signal
Piezoelectric Biosensors
- Biological molecules are coated onto a probing surface
- The sensing molecules are held in place with the help of non-interfering membrane
- Then, the sensing molecules react appropriately to the compound to be detected and produces an electrical signal proportional to the quantity being measured
- Electrochemical biosensors can employ various types of transducers (Potentiometric, Amperometric, Impedimetric)
- Converting the chemical information into a measurable electrical signal
Electrochemical Biosensors
