operational aspects Flashcards
What is a ROC curve?
receiver operating characteristics curve shows either how different detectors respond compared to the same parameters, or how the same detector changes its detection ability in different environments when controlled for same detection confidence and fixed response time
closet to Y axis, the more real alarms are being seen
closer to the x axis, the more false alarms present
what is a detection assay?
a way of qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of a target entity
Describe a sampling system
a system that autonomously or with human interaction through a series of agreed processes, can take a sample from an environment requiring testing, use one or more sensors to try to identify threats, then provide an response to an analyst.
What the characteristics of a biosensor ? 14 points
specificity
sensitivity
speed
cost
reliability
ease of manufacturing
size weight
power and consumables
ability to work in complex mixtures
low false positive rate
multianalyte detection
continuous/batch sensing
ease of operation
viability (live vs dead organisms)
What is meant by the response time
time taken from a sensor reaching the limit of detection to generating an alarm
provide a graphical representation of response time
What is LOD?
limit of detection or detection threshold - the minimum agent concentration required for a sensor to generate an alarm.
why is LOD important?
because it is the key trigger point for a system to enter an alert state
What is a spider chart used for?
demonstrating the results of 12 specifications of one or more sensors
what is a spider chart?
12 spoked wheel where each spoke is a measurable requirement for the sensor system. usually the further from the centre the better the system
12 specifications of a spider chart?
weight
power consumption
Unit cost
reliability (MTBF)
Operating costs
MTBM
false positive rate (low dose rate)
false positive rate (high dose rate)
response time
detection confidence
sensitivity
size
Explain deployment analysis?
assessment of 18 cardinal points to provide a final summary of how effective a system is, in ability to detect, but also maintain, continuously function and cost benefit
units for weight
Kg though dependant on system in vivo could be mg, platform could be tonnes
units for power consumption
watts
unit for unit cost
£ or currency of country using device. that said, $ cost does help as an internationally understood baseline for most costings
What is MTBF?
mean time between failures, or the average time between repairable failures of a technology product
unit of MTBF
months, though could be context dependant to secs to years
units for operating costs
£ per year
What is MTBM
mean time between maintenance
unit of MTBM
weeks, though could be system dependant
unit of false positive rate
number per year, though could be context dependant, so covid with national screening policies could be rate per day
response time unit
seconds
unit of detection confidence
percentage calculated from confusion chart and ROC measurements
unit for sensitivity
ACPLA - Agent Containing Particle per Litre of Air
unit of size
m^3
Is there such a thing as a one size fits all sensor?
no, and usually the opposite is true, should a sensor be described as a one size fits all, then it usually fails to meet the minimum requirements for any application.
Define noise
is fluctuation in sensor responses due to factors that are independent of the measurement environment.
a signal to noise ration of more than 1 is important, though in some cases not necessary/ possible. in these cases more processing like conducting a Fourier transform on the data is required, but this does affect the fidelity of the output.
define clutter
is the sensor response to all factors associated with the
measurement environment other than the agent.
define signal
is the sensor’s response to the agent.
18 cardinal points specifications for a bio sensor
specificity
selectivity
sensitivity
speed of response
stability
reproducability
repeatability
reliability
range
resolution
low false positive rate
multi analyte detection
continuous/batch sensing
ease of operation
viability
ease of manufacture
size weight power
cost
5 S’s of cardinal points
specificity
selectivity
sensitivity
speed of response
stability
4 R’s of cardinal points
Range
resolution
repeatability
reliability
8 multi letters of cardinal points
low false positive rate
multi analyte detection
continuous/batch sensing
ease of operating
viability
ease of manufacturing
SWAP (size weight and power)
Cost
Summary of cardinal points (13 points)
inital cost
operating cost
response time
limit of detection
power consumption
mission duration
consumables
maintenance
reliability
ruggedness/operationally hardened
form factor
environmental considerations
