Microbial Detection Arrays
October 23rd, 2006
Aerospace Senior Projects
University of Colorado - Boulder
1
Team Members
•
•
•
•
•
•
•
•
Elizabeth Newton – Project Manager
Shayla Stewart – Systems Engineer
Steven To – Chief Financial Officer
Dave Miller – Fabrication Engineer
Ted Schumacher – Lead Thermal Engineer
Jeff Childers – Lead Structural Engineer
Charles Vaughan – Lead Electrical Engineer
Sameera Wijesinghe - Webmaster
2
Briefing Overview
Jump
to
•
•
•
•
•
•
•
•
•
Overall Objectives
System Design Alternatives
Design-To Specifications
Thermal Design Options
Structural Design Options
Electrical Design Options
Project Feasibility and Risk
Project Plan
Appendices
Look for me
for further info
3
Overall Objectives
4
Picture from www.physics.byu.edu
Objectives Overview
• Objective: To design and build a field-ready unit capable of
providing a testing environment for electrochemical sensors
to detect microbial life by soil analysis
• Deliverables:
– Field-ready unit
– Test data verifying requirements
– Operational manual for use
Electrochemical sensors
• Sensors developed by Tufts University and BioServe
– Sensors analyze soil for metabolic indicators such as pH and chemical
composition and convert them to electronic signals
– Assumes that life only needs water and nutrients found in native soil to
metabolize
5
Functional Diagram
Geological Sample
•
•
Soil Sterilization
•
•
Inoculation
Sample
Temperature Control
Power
•
Reagent Water
Sensors
Test Chamber
•
Control Chamber
Mixer
Mixer
Temperature Control
Temperature Control
Data Acquisition
and Control
•
Accept soil
Sterilize soil using
an autoclave
Add reagent water
Move soil to
reaction chambers
Add non-sterile
inoculation sample
to test chamber
Mix soil and water
while starting
temperature
control
Testing lasts for
two weeks
6
Functional Requirements
• Must be capable of
performing in extreme Earth
conditions
– McMurdo Bay, Antarctica
-10°C to 2°C (during summer)
– Atacama Valley, Chile
-6°C to 38°C
Pictures from Wikipedia.org
• Must provide and function
with power comparable to
next-generation Mars
science rovers (30 Watts)
• Must be portable (30 kg)
7
Assessment of System Design
Alternatives
Pro of cost, mass, and volume
• Quantitative analysis
-Reaction chambers at same temperature
based on rough estimates
-No need to heat/cool each chamber individually
Con
• Ultimately, complexity
-No waybecame
to correct if primary
one chamberconsideration
is warmer than the
Environmental
Controls
Sterilization
Chamber
other
Pro
-More volume to heat/cool
Shared
-No need for extra environmental chamber
Con
-Each reaction chamber must be heated/insulated
Pro
Separate
Overall
Architecture:
-Only one chamber must be
fabricated
-Only needs one heater •Shared Environment
Con
•Separate
Sterilization
-Soil must be separated into
test/control
chambers after
Chambers
sterilization
Shared
Pro
-No need for soil separation: reduced complexity
Con
-Two chambers and two heaters
Separate
8
System Design Alternatives
End Result
• Separate Autoclaves
• Shared Environment
9
Design-To Specifications
• Thermal Subsystem
– Mass: 16.3 kg
– Volume: 0.096 m3
– Cost: $660
• Structural Subsystem
(excluding chassis)
– Mass: 11.3 kg
– Volume: 0.00293 m3
– Cost: $280
• Electrical Subsystem
(excluding power supply)
– Mass:0.30 kg
– Volume:0.00045 m3
– Cost:$1340
• Overall System
– Mass:27.9 kg
– Volume:0.09938 m3
– Cost:$2280
• Total Funds: $8000
10
Overall System Architecture
Autoclaves
Water
Chamber
Pump
Inoculation
Chamber
Test
Chambers
DAQ/Power
TEC
11
Work Breakdown Structure
MiDAs
Thermal Subsystem
Structural
Subsystem
Electrical Subsystem
Thermal Control
Materials
Power
Insulation
Soil/Water Transport
Data Acquisition
Mixing
Sensors
12
Thermal Design Options
Pictures from melcor.com, minco.com, wikipedia.org, energysolutionscenter.org
13
Insulation Options
• Insulation applications
– Autoclave chambers
– Environmental chambers
– Reagent water chamber
– Inoculation sample chamber
• Insulation Requirements
– Minimize power needed to heat chambers
– Protect electrochemical sensors from heaters
• Criteria (order of importance)
1. Volume (thermal conductivity, k)
2. Complexity
3. Cost
14
Insulation Option
Pros and Cons
Pros
Silica Aerogel
Thermal Coat Ceramic
Cons
-Very low thermal
conductivity
-Expensive
-Moisture resistant
-Adds almost no volume
because it is painted on
-Complicated
application
Fiber Board (Sindayno)
-Very low density
-350
-Thermal conductivity is
higher than that of air
Additional Options for Heating and Cooling
15
Structural Design Options
16
Pictures from trendir.com, polypenco.co.jp, sonozap.com, sciencelab.com, parker.com
Material Options
• Material applications
– Autoclave chambers
• Must be able to withstand high temperatures and
pressures
• Must be corrosion-resistant
– Environmental, inoculation, and reagent water
chambers
• Need to be lightweight
– Reaction chamber
• Must be able to be sterilized
• Must be inert
• Criteria (order of importance)
1. Mass
2. Complexity (machineability)
3. Cost
17
Material Pros and Cons
Pros
Cons
-Low density
-High yield strength
-Easy to machine
-Could not withstand
contact with heating
elements
-Somewhat expensive
316 Stainless Steel
-High strength
-Very high melting
temperature
-Relatively inexpensive
-High density
Ultem 1000
-Low density
-High yield strength
-Easy to machine
-Relatively inexpensive
-Could not withstand
contact with heating
elements
Polysulfone
Additional Options for Soil/Water Transportation and Mixing
18
Electrical Design Options
Pictures from spectrolab.com, fuelcellstore.com, dpie.com, weedinstrument.com
19
Power Supply Options
• Power supply requirements
– Power supply must provide 30 W of
power
– Must power the MiDAs instrument for
duration of experiment (17 days)
• Criteria (order of importance)
– Cost
– Mass
– Volume
20
Power Supply Pros and Cons
Pros
Cons
-Very high energy density
-Safety and logistic issues
-Switching out tanks
-Expensive
-High energy density
-Less complex
-Very large and heavy
-Requires a recharge system
Lithium Ion
Battery
-Very high energy density
-High demand
-Requires a recharge system
-Problems holding charge with age
Dual Junction
Solar Cells
-Safe, relatively simple
-Can be used to recharge
batteries
-Requires sunshine
Fuel Cell
Sealed Lead Acid
Battery
Additional Options for Data Acquisition and Pressure/Temperature Sensors
21
Feasibility and Risk
Picture from http://www4.macnn.com/games/gamecenter/risk2/s_01_lrg.jpg
22
Project Risk Assessment
Mitigation Factors
X
Material
X
Soil Handling
X
X
X
X
X
X
Power Supply
X
Data Acquisition
X
Sensors
X
Green Subsystems= Low Risk
X
X
X
X
X
X
Mixing
High Power
Use
Insulation
Hard to
Obtain
Thermal Control
Difficult
Analysis
Expensive
Lack of
Expertise
Easy to
Machine
Simple
Easy to
Obtain
Inexpensive
Lots of
Options
Subsystem
Risk Factors
X
X
X
X
X
X
X
X
X
X
Yellow Subsystems = Medium Risk
Red Subsystems= High Risk23
Autoclave Feasibility Assumptions
– Fluid inside is only water (high specific heat of water will
give maximum boundary)
– Insulation radius = 10 cm of material
(thermal conductance of k = 0.012 W/m °C)
– Internal and external losses and safety margin = 2.4W
(20% of heating/cooling capacity)
– Specific heat (Cp) for 316 steel = 452 J/kg K
– Specific heat (Cp) for water = 4230 J/kg K
– Heater uses 12 W per chamber
– Standard autoclave techniques implies
• 121°C, hold for 15 min
• Cool to 20°C, hold for 24 hours
• Repeat 3 times
24
Autoclave Feasibility Analysis
h2  25
W
m 2C
Rconduction =
Thickness
kA
Rconvection 
1
 0.427 C
W
h2 Aoutside
= 79.8 C/W
Rtotal  Rconduction  Rconvection  79.82 C
Q
Tinside  Tsurroundings
Rtotal
 1.64 W
U sys  U steel  U water  Q
W
• Time to heat from -10°C to
121°C = 3.9 hours
• Time to cool to 20°C = 117
min with active cooling
• Power:
– 3.9 amp hours to heat
– 0.04 amp hours to hold
for 15 minutes
– 1.95 amp hours to cool
– 3.36 amp hours to hold
for 24 hours
Q  [( m)(c p )(T2  T1 )] steel  [( m)(c p )(T2  T1 )] water
25
Autoclave Solution and Verification
• Solution:
– Sterilization chamber mock-ups will be
made and tested with various heaters and
insulation to verify that it is possible to
achieve 121°C
• Verification:
– Temperature and pressure sensors will be
used to verify that a sand/water solution
can reach 121°C on 30 W of power
26
Autoclave Power Summary
Power Summary (Sterilization Phase)
30
25
Autoclave Heater/Cooler 1
Autoclave Heater/Cooler 2
DAq
Temp/Pressure Sensors
Total Power
20
15
10
5
18
00
15
00
12
00
90
0
60
0
30
0
0
0
Power Consumption (W)
35
Operation Time (min)
27
Mixing Feasibility Analysis
• Requirement:
– Soil and water must be mixed within the reaction
chambers
• Reduces boundary layer so electrochemical sensors can
read correctly
• Prevents soil sedimentation
• Problem:
– Difficult to find mixers small enough to fit in
reaction chambers
– Flow pattern difficult to analyze without testing
– Unknown if ultrasonic mixers can be used at
appropriate frequency
– Magnetic stirrers may affect electrochemical
sensors
28
Mixing Solution and Verification
• Solution:
– Mock-ups of reaction chambers will be prototyped
and tested with various mixers
– Different soil granularities will be tested
– Various mixing regimes will be tested
• Continuous mixing
• Pulsed mixing
• Verification:
– Flow patterns and soil sedimentation will be visually
analyzed to show that various types of mixing
regimes and mixers provide adequate stirring
29
Project Plan
Picture from http://www.connectedconcepts.net/clip%20art/Project%20Plan.gif
30
Organizational Chart
Project Manager
Elizabeth Newton
Chief Financial Officer
Steven To
Systems Engineer
Shayla Stewart
Safety Engineer
Chuck Vaughan
Thermal Subsystem
Electrical Subsystem
Structural Subsystem
Thermal Lead
Ted Schumacher
Electrical Lead
Chuck Vaughan
Structures Lead
Jeff Childers
Dave Miller
Steven To
Elizabeth Newton
Jeff Childers
Sameera Wijesinghe
Sameera Wijesinghe
Fabrication Engineer
Dave Miller
Shayla Stewart
31
Schedule Through CDR
32
Schedule Through CDR
33
Schedule Past CDR
• Machining:
– Assume one chamber machined per week
– Last Machining Day – March 16, 2007
• Testing:
– Subsystem testing can begin as soon as each
chamber is constructed
– Overall testing: March 16, 2007 – April 17, 2007
• Final Review – April 17, 2007
• ITLL Expo – April 28, 2007
• Final Report – May 3, 2007
34
Conclusions
• Project is feasible
– Budget is one-quarter of funds
– Mass is 34 kg, which is portable
– Initial calculations and research indicate that high risk
subsystems (mixing and autoclaving) are challenging
but possible
• Further analysis through prototyping will be performed before
CDR
– System is capable of performing in specified
environments
– System is capable of performing with 30 W of power
– Many options are available to meet each requirement
• This allows off-ramps in case some options are dismissed
during design
35
Questions/Comments?
Picture from http://content.answers.com/main/content/wp/en/thumb/5/5b/250px-Nasa_mer_marvin.jpg36
References
1. Cengel, Yunus. Introduction to Thermodynamics and Heat Transfer.
McGraw-Hill. University of Nevada, Reno. 1997
2. Gilmore, David. Spacecraft Thermal Control Handbook. Aerospace
press. El Segundo, California. 2002
3. www.aerogel.com
4. www.dimondsystems.com
5. www.matweb.com
6. www.mcmaster.com
7. www.melcor.com
8. www.minco.com
9. www.omega.com
37
Appendix Table of Contents
•
•
•
•
•
•
System Architecture Options
Chamber Geometries
Verification Methods
Power Model and Budgets
Operational Environment
Subsystem Options, Trade Studies, and
Pros and Cons
38
Appendix A: System Parameter
Estimates
Mass (g)
Volume (mL)
Cost
Reaction Chamber
127
100
$11
Large Autoclave Chamber
4013.5
500
$125
Small Autoclave Chamber
2006.75
250
$63
Soil Transport
88
100
$2.60
Motor
150
200
$20
Moving Sensor Package
254
200
$22
Environmental Sensors
10
50
$200
39
Assessment of System
Design Alternatives
Quantitative Analysis of Options
Mass
(g)
Volume
(mL)
Cost
Shared Environment,
Shared Sterilization
900
4444
$150
Separate Environment,
Shared Sterilization
1200
4504
$1,350
Separate Environment,
Separate Sterilization
1400
4612
$1,750
Shared Sterilization,
Separate Environment
1300
4592
$1,350
Mass, volume, and cost figures do not include components that all options
need the same number of, such as a reagent water tank and mixers.
40
Option A
• Sterilization and
testing occur in
same chamber
• Requires:
– 1 large
autoclave
– 2 moving sensor
packages
– 2 motors
– 2 environmental
sensors
Mass: 1000 g
Volume: 4842 mL
Cost: $600
• High complexity
from moving
sensor
packages
41
Option B
• Shared
sterilization,
separate
environment
• Requires:
– 1 large
autoclave
– 2 reaction
chambers
– 2 soil transport
tubes
Mass: 900 g
Volume: 4444 mL
Cost: $150
42
Option C
• Shared
sterilization,
separate
environment
• Requires:
– 1 large autoclave
– 2 reaction
chambers
– 2 soil transport
tubes
– 6 environmental
sensors
43
Mass: 1200 g
Volume: 4504 mL
Cost: $1350
Option D
• Separate
sterilization,
separate
environment
• Requires:
– 2 small
autoclaves
– 2 reaction
chambers
– 3 soil transport
tubes
– 8 environmental
sensors
Mass: 1400 g
Volume: 4612 mL
Cost: $1750
44
Option E
• Separate
sterilization,
shared
environment
• Requires:
– 2 small
autoclaves
– 2 reaction
chambers
– 3 soil transport
tubes
– 6 environmental
sensors
45
Mass: 1300 g
Volume: 4592 mL
Cost: $1350
Autoclave Chamber Geometry
• Assumptions of a possible design:
– Chamber is made of 316 stainless steel
– 5 mL water added to chamber for use in autoclaving
– 15 mL space provided so sample is not tightly packed
– Chamber is a cylinder
• Dimensions:
– Total internal volume of chamber = 45 mL
– Internal diameter = 2.54 cm
– External diameter = 3.04 cm
– Wall thickness = 0.25 cm
– Length = 9.38 cm
– Mass = 0.19 km
46
Reaction Chamber Geometry
• Assume:
– Chamber is made of Ultem 1000
– Chamber wall thickness of 0.5 cm
– Inside chamber geometry is a
cylinder
– 20 mL additional space for mixing
(70 mL total volume)
• Dimensions:
– Walls: 0.5 cm thick
– Outside diameter = 3.95 cm
– Height = 11.28 cm
– Mass = 0.0866 kg
Drawings by Jake Freeman
47
Environmental Chamber Geometry
Top View
Side View
• Assume:
– Chamber is a cube
containing both reaction
chambers
– Buffer around chambers is
3 cm with 2 cm between
them
• Dimensions:
– Height: 17.28 cm
– Depth: 9.95 cm
– Width: 11.95 cm
– Volume: 2054.635 cm3
48
Reagent Water Chamber Geometry
Side view
• Assume:
– Chamber is a cylinder
– Water expands upon
freezing
• Dimensions:
– Height: 2.1 cm
– Radius: 3.0 cm
– Volume: 60 cm3
49
Verification Methods
Requirement
#
Title
Verification
Method
PDD 4.1
Reaction Chamber
Volume
I, D
Verification will be through simple volume measurement.
PDD 4.2
Reaction Chamber
Temperature
A, T
Verification will be through thermal analysis of the reaction
chamber geometry and test by means of simple temperature
sensors.
PDD 4.3
Reaction Chamber
Pressure
A, T
Verification will be through thermal analysis of the reaction
chamber geometry and test by means of simple pressure
sensors.
PDD 4.4
Reaction Chamber
Sensor Capability
A, I
Verification will be through analysis of the chamber geometry and
by visual means.
A, I
Verification will be through analysis of the flow pattern generated
during mixing and basic prototype inspection testing.
Verification
PDD 4.5
Reaction Chamber Mixing
Capability
PDD 4.6
Reaction Chamber MultiUse Port
A, I
PDD 4.7
Reaction Chamber
Material
A
Verification will be through structural and thermal analysis of the
reaction chambers.
PDD 4.8
Geological Sample
Volume
T
Verification will be through measuring soil before it is added to the
autoclave chambers
PDD 4.9
Inoculation Sample
Volume
T
Verification will be through measuring inoculation sample before it
is added to the inoculation sample chamber
PDD 4.10
Inoculation Sample
Reception
A, D
Verification will be through analysis of the chamber geometry and
by visual means.
Verification will be through analysis of soil transport and
demonstration to show sample delivery.
50
Verification Methods
Requirement
#
Title
Verification
Method
PDD 4.11
Reaction Sample
Handling
A, T
Verification will be through thermal analysis of the autoclave
chambers and testing by means of temperature and pressure
sensors.
PDD 4.12
Inoculation Sample
Handling
A, T
Verification will be through thermal analysis and testing by
means of temperature sensors.
PDD 4.13
Reaction Sample
Delivery
A, D
Verification will be through analysis of soil transport and
demonstration to show sample delivery.
PDD 4.14
Inoculation Sample
Sterility
A, D
Verification will be through analysis of soil transport and
demonstration to show sample delivery.
PDD 4.15
Reagent Water
Containment
A, T
Verification will be through thermal analysis and test by means
of temperature sensors.
PDD 4.16
Reagent Water Delivery
A, D
Verification will be through analysis of soil transport and
demonstration to show sample delivery.
PDD 4.17
Reagent Water
Temperature
A, T
Verification will be through thermal analysis and test by means of
temperature sensors.
PDD 4.18
Sensor Integration
A, I
Verification will be through analysis of the reaction chamber
geometry and simple volume measurement.
PDD 4.19
Sensor Data Collection
Rate
A, T
Verification will be through analysis and testing of the command
software.
PDD 4.20
Sensor Data Acquisition
A, T
Verification will be through analysis and testing of the command 51
software.
Verification
Verification Methods
Requirement
#
Title
Verification
Method
PDD 4.21
Sensor Data
Accessibility
D
PDD 4.22
MiDAs Status
Warnings
A, T
Verification will be through analysis and testing of the
command software.
PDD 4.23
MiDAs Command
A, T
Verification will be through analysis and testing of the
command software.
PDD 4.24
Field Power
A, T
Verification will be through analysis of the power supply and
testing through standard electronics lab equipment.
PDD 4.25
Laboratory Power
D
Verification will be through a demonstration of the instrument
with the external laboratory power supply.
PDD 4.26
Nominal Power
Consumption
A, T
Verification will be through analysis of the power consumption
of each component and testing.
PDD 4.27
Peak Power
Consumption
A, T
Verification will be through analysis of the power
consumption of each component and testing.
PDD 4.28
Unit Disassembly
D
Verification will be through a demonstration of the instrument
disassembly.
PDD 4.29
Operational Cycle
D
Verification will be through a demonstration of a complete
operational cycle.
PDD 4.30
Operational
Environment
A
Verification will be through thermal analysis of the
surrounding environment.
Verification
Verification will be through demonstration of data transfer.
52
Power Model
Power Summary (Experiment)
25
Thermal
15
Structures
Electronics
10
Total
5
96
0
10
80
12
00
13
20
14
40
15
60
16
80
18
00
19
20
84
0
72
0
60
0
48
0
36
0
24
0
0
0
12
0
Power Consumption (W)
20
Operation Time (min)
53
Mass Budget
Autoclave (316 Steel) x 2
9 kg
Test/control/water chamber (Ultem1000) x 3
2.13 kg
Inoculation chamber (Ultem1000)
0.19 kg
Autoclave Insulation (Aerogel)
13.4 kg
Test/control Insulation (Aerogel)
2.9 kg
DAQ
0.285 kg
Sensors
0.125 kg
Extra (Ultem1000 Chassis)
6 kg
Power supply
4 to 30 kg
Total (excluding power supply)
34 kg
54
Cost Budget
Heaters x 4
$160
Autoclave (316 Steel) x 2
$240
Test/control/water chamber
(Ultem1000) x 3
$40
Inoculation chamber
(Ultem1000)
Included above
Autoclave Insulation
(Aerogel)
$500 (min
purchase)
Test/control Insulation
(Aerogel)
Included above
DAQ
$995
Sensors
$345
Total
$2280
Total Funds:
$4000 from Senior Projects
$4000 from BioServe
Total: $8000
55
Operational Environment
Laboratory
McMurdo
Bay,
Antarctica
(summer)
Atacama
Valley, Chile
(Altitude =
2000 m)
Temperature
(max)
30°C
2°C
38°C
Temperature
(min)
20°C
-10°C
-6°C
Pressure
(avg)
1 atm
1 atm
0.802 atm
56
Thermal Control Design-To Requirements
Requirement
#
PDD 4.2
PDD 4.11
PDD 4.15
PDD 4.17
PDD 4.30
Title
Requirement
Importance
Reaction Chamber
Temperature
Each reaction chamber
shall be controllable within
a range of 4°C to 37°C
with an accuracy of ±1°C.
This environment is
acceptable for the possible
life to metabolize and
reproduce.
Reaction Sample Handling
The reaction samples shall
be sterilized in accordance
with standard Autoclave
techniques.
This is the best method of
sterilization for killing the
known forms of life.
Reagent Water
Containment
The sterile reagent water
shall be completely
contained in both solid and
liquid form.
This prevents the reagent
water container from
bursting if the water
freezes.
Reagent Water
Temperature
The reagent water shall be
delivered to the reaction
chambers at a
temperature not to exceed
60°C.
The electrochemical
sensors can't withstand
temperatures above 60°C.
Operational Environment
MiDAs shall be able to
operate in environments
ranging from Antarctica to
Atacama Valley in Chile.
These are the likely test
sites for the MiDAs
instrument.
57
Heating/Cooling Options
•
Heating applications
– Autoclave chambers: must reach 121°C and hold
for 15 minutes
– Environmental chambers: must maintain
temperatures from 4°C to 37°C for 14 days
•
Cooling applications
– Autoclave chambers – must be cooled from 121°C
to 20°C
– Environmental chambers – must maintain
temperatures from 4°C to 37°C for 14 days
•
Criteria
1. Volume
2. Power consumption
3. Risk
4. Complexity
5. Mass
6. Cost
58
Heating Option Pros and Cons
Pros
Strip
Cons
-Strong sheath
-Difficult to find small sizes
-Good at heating air
-Custom length and
resistance needed
-Cheap
-Easy to custom-order
-Kapton coating
-Clamping system required
-Best used for conduction
heating
Immersion
-Direct heating for
substance
-Heating element may get in
the way of mixer
Cartridge
-High watt density
-Requires tight tolerances for
placement
-Strong sheath
-Small sizes don’t have high
wattages
Tubular
Tape or flexible
Band
59
Cooling Option Pros and Cons
Pros
Cons
-Does not require power
-Simple
-Geometry of chambers
may limit effectiveness
-Longest cooling time
Heat Switch
-Allows most sides of
chamber to be insulated
while still allowing cooling
-Complex implementation
-Difficult to find data
Thermoelectric
Cooler
-Concentrated cooling
power
-Allows most sides of
chamber to be insulated
while still allowing cooling
-Requires power
Passive
60
Heating Options
Heating
application
Typical off the
shelf example
Power of
example
Overall Size of
example
(inches)
Weight of
example
(lbs)
Price of
example
Strip
Gases or solid
surfaces
Omega PT512/120
2.5W at 12V
5.5 x 1 x 1.5
0.4
$30
Tubular
Gases
Omega TRI1212/120
3.3W at 12V
0.246 O.D.x 12
long
0.2
$28
Tape or flexible
Solid surfaces or
possibly gases
Minco
HK5464R4.9L1
2A
29.39W at
12V
3x3
0.01
$33.80
Immersion
Liquids
Omega RI100/120
2W at 12V
Internal heating
component =
tube 1.5 long x
0.625 O.D.
3
$115
Cartridge
Solids
Omega CSS01235/120
0.7W at 12V
0.124 O.D. x 2
long
0.06
$26
Band
Solids in
cylindrical form
Omega MBH1215200A /120
4W at 12V
1.25 I.D. x
1.5 width
0.87
$32
61
Cooling Options
Typical off
the shelf
example
Power of
example
Overall Size
of example
(inches)
Weight of
example
(lbs)
Price of
example
Passive
Cooling
NA
0
0
0
$0
Heat Switch
Starsys
Research
Diaphragm
Thin Plate
Switch
Thermoelectric Melcor CP1.0Cooling
127-05L-1-W5
May not be available at this time
16 W
30 mm x 30
mm x 3.2 mm
0.024
$15.54
62
Insulation Options
Density (kg/m^3)
Cost
K (W/m-K)
Silica Aerogel
5-200
$325 for 50 g + $30
shipping
0.016-0.03
TC- Ceramic
Unknown
Unknown
0.097
Fiber Board (Sindayno) -350
1900
Unknown
0.63
Air
1.168
NA
0.025
63
Material Design-To Requirements
Requirement
#
Title
Requirement
PDD 4.7
Each reaction chamber
shall be manufactured out
of a list of materials
Reaction
provided by BioServe.
Chamber
This list includes, but is not
Material
yet limited to, Polysulfone,
Pharmed, 316 stainless
steel, and Ultem 1000.
PDD 4.11
Reaction
Sample
Handling
The reaction samples shall
be sterilized in accordance
with standard Autoclave
techniques.
Importance
All of these materials are
able to be autoclaved, have
high resistance to
corrosion, and are FDA
approved for food service
or medical use.
This is the best method of
sterilization for killing the
known forms of life.
64
Material Options
Density
(g/cm3)
Yield
Strength
(MPa)
Maximum
Temperature
(°C)
Cost per kg
Machineability
Polysulfone
1.24
74.9
149-180
$5.93
Very good
316
Stainless
Steel
8.027
205
899
$2.32
Fair
Ultem 1000
1.27
110
170
$3.84
Very good
65
Soil Handling Design-To Requirements
Requirement #
Title
Requirement
PDD 4.8
Geological Sample Volume
Each reaction chamber shall receive
no less than 5 mL and no more than
25 mL of geological sample.
PDD 4.9
Inoculation Sample Volume
The test chamber shall receive a
maximum of 1 mL of inoculation
sample.
Importance
5 mL is the about the minimum
amount of soil to obtain good results.
25 mL is still small enough amount to
keep the experiment light and
portable.
The nonsterile inoculation sample is
what could contain life.
The test chamber shall receive the
inoculation sample through
established aseptic techniques.
The user needs to know that any
detected life forms were already
present in the soil, not transferred to
the soil through the transportation
method.
Reaction Sample Delivery
One pre-measured reaction sample
shall be delivered to the test chamber
and one pre-measured reaction
sample shall be delivered to the
control chamber. Both samples shall
maintain sterility throughout delivery.
Having equal amounts of soil in each
reaction chamber helps maintain
uniformity between the test and
control. Once the soil is sterilized, it
has to remain sterile so that no life
forms are introduced.
Inoculation Sample Sterility
The inoculation sample shall be
aseptically delivered to the test
chamber.
The inoculation sample can't pick up
any living organisms from the MiDAs
instrument. If life is detected, one
needs to know that it was originally in
the soil or the experiment is useless.
PDD 4.16
Reagent Water Delivery
The MiDAs shall aseptically deliver
no more than 50 mL (within ± 5%
accuracy) of sterile reagent water to
each reaction chamber.
The delivery must be aseptic, so that
no living organisms are transferred to
the reagent water.
PDD 4.28
Unit Disassembly
MiDAs shall be able to be taken apart
so that it may be sterilized and
reassembled for multiple Earth tests.
The instrument needs to be reusable.
PDD 4.10
PDD 4.13
PDD 4.14
Inoculation Sample Reception
66
Soil/Water Transportation Options
• Soil and water transportation includes pumps,
tubing, and valves
• Soil/water handling applications
– Reagent water transferred to sterilization and
inoculation chambers to flush soil
– Soil and water mixture transferred from
sterilization and inoculation chambers to reaction
chambers
• Criteria
1. Complexity (autonomy)
67
Soil/Water Transportation
Pros and Cons
Cons
Sealing
Gates
Pros
Push/Pull
Solenoids
-Simple
-High reliability
-Low cost
-Small
-Not variable
Electromagnets
-Simple
-High reliability
-Med cost
-Small
-High power usage
Motor
-Compatibility
-Small
-Low cost
Pressure
Sealing
-High reliability
-Two way
-Complex setup
-Less parts
-Low reliability
-Complex setup
-One way
-May have interference with sensors
Magnetic
Sealing
-Complexity
-Low reliability
68
Soil Transportation Options
Gate Options
Voltage
Power
Complexity
Reliability
Size
Push/Pull Solenoids
3VDC
3W
low
high
d = 25.5mm
h = 28.9mm
Electromagnets
12VDC
?
low
high
d = 35mm
h=~45mm
Motor
12VDC
58 RPM
low
high
d =6.3 mm
Belt System
N/A
N/A
high
med
custom
Pressure Plug
N/A
N/A
low
high
custom
Push/Pull Solenoid
3VDC
3W
low
high
d = 25.5mm
h = 28.9mm
High Torque Motor
TBD
TBD
low
high
d = 127mm
h = 127mm
Belt System
N/A
N/A
high
med
custom
Electromagnets
12VDC
?
high
high
very large
High Compression Spring
N/A
N/A
high
low
custom
Motor System
Sealing Options for
Autoclave
Pressure Sealing
Magnetic Sealing
69
Mixing Design-To Requirements
Requirement
#
PDD 4.5
PDD 4.28
Title
Requirement
Importance
Reaction
Chamber
Mixing
Capability
Each reaction chamber
shall have mixing
capability such that each
geological sample is
evenly distributed within
the fluid while movement
is present at each sensor
location.
The fluid must be mixed so
that the sensor readings are
as accurate as possible. The
fluid must also move at each
sensor so that the boundary
layer around the sensors is
broken down, which is
necessary to get a reading.
Unit
Disassembly
MiDAs shall be able to be
taken apart so that it may
be sterilized and
reassembled for multiple
Earth tests.
The instrument needs to be
reusable.
70
Mixing Options
• Mixing applications
– Soil in reaction chambers must be stirred
• Electrochemical sensors need fluid
movement to function
• Prevents sedimentation to soil
• Criteria (order of importance)
1. Volume
2. Power usage
3. Risk
4. Cost
71
Mixing Option Pros and Cons
Pros
Cons
Ultrasonic
-BioServe may provide
-Does not disrupt ISE’s
-Ruptures cell membranes above
18 kHz
-Expensive
-Lack of prior experience
Magnetic
-No known machining required
-Does not require probe through
top or bottom of reaction
chambers
-ISE interference pending test
-Magnetic Martian soil
Mechanical
-Known flow-pattern
-Does not disrupt ISE’s
-Common use / more experience
-Soil could clog mechanism
-Most COTS mixers are too large
72
Mixing Options
Ultrasonics
Volume
Cost
Power
PCB: 5" x 2 3/4" x 1"
$1295*
variable
Probe: 0.850" diam, 4 1/2" long
Probe tip: 1/8" diam x 2" long Ti
alloy
Magnetic
4.8” x 4.8” x 1.8”
Unknown
Mechanical
0.8 mm diameter impeller
Unknown
73
Power Supply Design-To Requirements
Requirement
#
Title
Requirement
Importance
Field Power
MiDAs shall provide its own power
(between 10 W and 30 W) in a field
setting.
MiDAs shall provide its
own power (between 10
W and 30 W) in a field
setting.
PDD 4.25
Laboratory
Power
MiDAs shall be capable of receiving
between 10 W and 30 W from an
external power supply in a laboratory
setting.
The instrument needs to
be capable of running in
a lab, as well as the field.
PDD 4.26
Nominal Power
Consumption
Nominal power consumption shall not
exceed 30 W.
This is based on
estimates of the Mars
astrobiology rover
PDD 4.27
Peak Power
Consumption
Peak power consumption shall not
exceed 30 W for more than 30
seconds.
This is based on
estimates of the Mars
astrobiology rover
Operational
Cycle
One operational testing cycle shall be
14 standard Earth days, not including
power-up, sterilization, and powerdown.
This is the time given for
the potential life to
reproduce and
metabolize.
PDD 4.24
PDD 4.29
74
Power Supply Options
Mass (kg)
Volume
(cm3)
Cost
Power
Provided
Time for
Delivery
Fuel Cell
1.133
637
$1769
30W @
12V
3-4 Weeks
Sealed Lead
Acid Battery
30
10577
$165
40 hrs,
30W @ 12
V
2-3 Weeks
Lithium Ion
Battery
8
4800
$40
30 W @
12V
2-3 Weeks
Dual Junction
Solar Cells
0.118 kg
(does not
include
backing)
Area =
30 cm2
$940 (to
charge)
30 W @ 12
V
2 Weeks
75
Data Acquisition Design-To Requirements
Requirement #
Title
Requirement
Importance
Reaction Chamber Sensor Capability
Each reaction chamber shall be
capable of supporting no fewer than 6
and no more than 18 electrochemical
sensors.
This is the number of electrochemical
sensors that will be provided by the
customer.
PDD 4.19
Sensor Data Collection Rate
The electrochemical sensors shall
have a data collection rate of 1
measurement per minute per sensor.
Since the experiment takes place over
14 days, a reading each minute from
each sensor is sufficient to
characterize the experiment results.
PDD 4.20
Sensor Data Acquisition
All data taken through the sensors
shall be collected and stored for
analysis.
The data will be analyzed after the
experiment is completed.
PDD 4.21
Sensor Data Accessibility
The scientific and engineering status
data shall be accessible to users
throughout the experiment.
The customer would like to be able to
look at the status of the experiment
while it is in progress.
PDD 4.22
MiDAs Status Warnings
MiDAs shall provide caution, warning,
and instrument status to external
ground support equipment.
This is necessary to be able to observe
the status of the instrument, as well as
detect errors.
PDD 4.23
MiDAs Command
MiDAs shall receive commands from
external ground support equipment.
The duration of the experiment is such
that it is not reasonable to have the
user initiate each step of the process.
Operational Cycle
One operational testing cycle shall be
14 standard Earth days, not including
power-up, sterilization, and powerdown.
This is the time given for the potential
life to reproduce and metabolize.
PDD 4.4
PDD 4.29
76
Data Acquisition Options
• Data acquisition applications:
– Must be able to give commands to
sensors, heaters, and soil transport
– Must be able to store data with a
collection rate of one sample per sensor
per minute
• Criteria:
– Power usage
– Cost
77
Data Acquisition Options
DAQ Cards
model
power
LabJack UE9
5 V or by
USB cable
$429
---
75mm
185mm
30mm
16 bit
---
2 week
shipping
by USB
cable
$99
---
75mm
115mm
30mm
12 bit
---
2 week
shipping
LabJack U3
price
Weight
Width
Length
Height
Resolution
Memory
Time
Embedded CPU with DAQ
Athena
10 W
$825
150 g
4.175"
4.45"
---
16 bit
128 MB
2 week
shipping
Poseidon
3.5 W
$995
---
4.528"
6.496"
---
16 bit
256 MB
2 week
shipping
Elektra
5.5 W
$750
108 g
3.55"
3.775"
---
16 bit
128 MB
2 week
shipping
Hercules
12 W
$500
285 g
8"
5.75"
---
16 bit
128 MB
2 week
shipping
78
Data Acquisition
Pros and Cons
Pros
Data Acquisition
Card
-Self powered (draws power from
computer)
-Embedded system
-Can provided variety of data
transfer options
Embedded CPU w/
-Can be used to store data until
Data Acquisition
testing complete
-Can provide accessibility to
autonomous control
Cons
-Requires additional
hardware
-Requires additional power
consumption
-Expensive
79
Pressure and Temperature
Sensor Options
• Pressure and temperature sensor applications:
– One of each sensor in the sterilization chambers
capable of withstanding high temperature
– One of each sensor in the each reaction
chamber
– One temperature sensor in the reagent water
chamber
• Criteria:
– Cost
– Power usage
– Temperature range
80
Temperature Sensor
Pros and Cons
Pros
Thermocouples
Thermistors
Resistance
Temperature
Detectors (RTD)
Cons
-Variety of types and configurations
-Low cost, wide availability
-Reliable
-Self-powered
-Can handle autoclave temperatures
-Requires a cold junction
compensator for calibration
-Sensor accuracy can reach
1°C at temperatures between
10°C and 40°C
-Better accuracy than
thermocouples and RTDs
-Loss of linearity
-Requires shielding from high
temperatures
-Requires current
-High accuracy
-Excellent stability and reusability
-Can be immune to electrical noise
-Requires shielding from high
temperatures
-Requires current to take
measurements
81
Temperature Sensor Options
Thermocouples
Volume
Cost
Weight
Diameter
Length
Temp
Range
Operation
Range
Accuracy
(1-40 °C)
5SRTC-TT (mini
connector)
$54
(5 pack)
---
0.51mm
1m
T
---
±1 °C
2 day shipping
available
TJ36 (autoclave
probe)
$92
---
1.6mm
1m
JKTE
---
---
2 day shipping
available
$15
---
2.8mm
60mm
-80 to
250 °C
---
±1 °C
2 day shipping
available
Height
Length
Width
25mm
2m
19mm
-73 to
260 °C
---
±0.5 °C
2 day shipping
available
Height
Length
Width
Model
Time
Thermistor
44005
RTD
SA1-RTD
$50
---
CJC
MCJ-T (battery
included)
$99
57 g
13mm
75mm
25mm
T
10-45 °C
---
2 day shipping
available
CJ-T (battery
included)
$170
75 g
12mm
75mm
49mm
T
10-50 °C
---
2 day shipping
available
82
Pressure Sensor
Pros and Cons
Pros
Gauge
Absolute
Differential
Cons
-Widely available
-Relatively cheap
-Measures pressure
relative to standard
atmosphere
-Measures pressure
relative to vacuum
-Widely available
-Relatively cheap
-Requires additional
sensors to measure
local conditions
-Slightly more
-Measures difference
expensive than gauge
between two locations
and absolute
83
Pressure Sensor Options
Pressure Sensors
Volume
Cost
Weight
Height
Length
Width
Temp
Range
Power
Accuracy
***
Time
PX138 *
$85
---
26.2mm
28.1mm
27.9mm
0 to 50
°C
8VDC
0.1%
0.5%
1 week shipping
PX139 *
$85
---
26.2mm
28.1mm
27.9mm
0 to 50
°C
5VDC
@2 mA
0.1%
0.5%
1 week shipping
PX140 *
$120
---
26.2mm
28.1mm
27.9mm
-18 to
63 °C
8VDC
0.75 %
0.15%
1 week shipping
Diameter
Length
12mm
57.9mm
-54 to
121 °C
24VDC
@ 15 mA
0.25%
0.25%
1 week shipping
Model
PX209 **
$195
---
84