Biosensors Quiz 1 Flashcards
What do physical sensors measure?
physical things such as force, pressure, temp
What does a chemical sensor do?
transform chemical energy into another form of energy that is useful, it is SELF contained and provides real time information, it performs recognition AND transduction
What is a chemical sensor/ analytical device that does not have a recognition function called?
It is called a concentration transducer
What is a biosensor?
An analytical device that turns a biological signal into an ELECTRICAL signal. It contains a biological recognition element BRE and a transducer. The sensing element and the transducer can be two distinct elements that are packaged together.
What is a molecular sensor/nanosensor?
a sensor that has two distinct units, one binds to analyte and the other changes some property of the analyte. Mol sensors are not chemical sensor because they miss the transducer, these are also called ADVANCED ANALYTICAL REAGENTS
What are the 5 biosensor components?
1) Bioreaction
2) Transducer to electrical signal
3) Amplifier
4) Processor probably by some chip
5) Displayed or used for actuation
What is an analyte or determinant?
A substance thats chemical properties are being measured and identified.
What does a bioreaction do?
Convert substrate to product
What occurs in affinity binding?
There is a reversible covalent bond between two chemical species.
What is ion recognition?
this method occurs when materials and reagents have an electric charge opposite to that of the analyte of interest.
What occurs with recognition by nucleic acids?
Nucleic acid hybridization, where a short nucleic acid (capture probe) is used to detect the analyte nucleic acid.
What occurs in recognition by enzyme?
involves substrate – enzyme complex formation, chemical conversion of bound substrate and product release.
What are the different assay formats?
Direct binding which includes immunoassay and hybridization
Sandwich assay
Displacement assay
replacement binding
What is Immunoassay format?
the antibody in the solution
binds to the immobilized antigen or vice versa.
What is hybridization assay format?
DNA in the solution, binds to complimentary DNA on the surface which is immobilized.
What is the sandwich assay?
This is when there are low molecular weight antigens that produce small signals or little changes, may work with two types of recognition elements
What is displacement assay?
the analog antigen is immobilized, then the antibodies that bind with this antigen leave and bind to antigens that are added to the solution
What is replacement binding?
Analog antigen is attached to a larger molecule, this is bound to the antibody refractive index probe, then the analyte replaces the RI and the change is measured
What is the difference between a sensing element and a recognition element?
A sensing element gives information about the chemical and it detects it, the recognition element is in a biosensor and it also gives the user information about the structure of the analyte.
What is the goal of a sensor?
TO OBTAIN A MARKETABLE PRODUCT
What are the two types of sensors based on portability?
Portable for field applications, implantable for in vivo monitoring for many biomedical applications
What is the difference between cheap and expensive sensors?
Smart sensors are integrated with a microelectronic circuit that can control the sensor parameters, perform data processing and interfacing with external devices
Cheap sensors disposable sensors, on the other hand, should secure batch reproducibility of the response characteristics – dip-in probe configuration
How can a sensor be maintained over a long period of time?
Carefully calibrate and condition after use
What do the figures of merit describe?
Indicates how much a sensor fits the expected performance, as far as the quality of results, response stability and ruggedness under storage and operation are concerned.
What does the confidence interval describe?
the scattering of the results
Why may bias start to occur in a sensor?
many factors that have to do with systematic errors
What is the difference between repeatability and reproducibility?
Repeatability is how well the biosensor can repeat the same tests under the same conditions for calibration over time. Reproducibility is how well the biosensor can do tests under different calibration conditions over time. Drift impacts REPEATABILITY
What is selectivity in a biosensor?
how well a sensor can pick out the analyte without being interfered with by the other components of the solution
What is sensitivity in a biosensor?
change in response vs change in concentration
What is response time?
Time elapsed since the analyte is added to a well – stirred, analyte free solution to the moment when the sensor response attains a practically constant value (typically 95% of the response in 1 – 60 seconds).
What is linearity?
Maximum linear value of the sensor calibration curve. Linearity ofthe sensor must be high for the detection of high substrate concentration.
What is the limit of detection?
the lowest concentration that the sensor provides valuable results
what is the limit of quantification?
the range that more reliable data is found
Dynamic range is what?
Between lower and upper LOD
What is flexibility of a biosensor?
ability of biosensor to use other transduction methods
What is the goal of flow analysis systems?
it analyzes a number of samples, a variation in concentration occurs
What are the two types of analysis?
Structural analysis uses a static/frozen in time as it’s drawback
Functional analysis is not frozen in time but it needs labeling of interactants, cannot follow processes in time
