# Presentation: 090502

## Nanotechnology for Space Exploration

- M. Meyyappan
- Chief Scientist for Exploration Technology

**Nanotechnology for Space Exploration**

## What is Nanotechnology?

- Nanotechnology is the creation of **USEFUL/FUNCTIONAL** materials, devices and systems (**of any size**) through control/manipulation of matter on the nanometer length scale and exploitation of novel phenomena and properties which arise because of the nanometer length scale:

*Source: K.J. Klabunde, 2001*

- •	Physical
- •	Chemical
- •	Electrical
- •	Mechanical
- •	Optical
- •	Magnetic
- •
- •

## Why Nanotechnology at NASA?

- •	Advanced miniaturization, a key thrust area to enable new science and exploration missions
- 		-		Ultrasmall sensors, power sources, communication, navigation,
- 				and propulsion systems with very low mass, volume and power
- 				consumption
- •	Revolutions in electronics and computing will allow reconfigurable, autonomous, “thinking” 	spacecraft
- •	Nanotechnology presents a whole new spectrum of
- 	opportunities to build device components and
- 	systems for entirely new space architectures
- 		-		Networks of ultrasmall
- 				probes on planetary surfaces
- 		-		Micro-rovers that drive,
- 				hop, fly, and burrow
- 		-		Collection of microspacecraft
- 				making a variety of measurements
- •	Nanomaterials and composites for civilian
- 	aeronautics.

## National Nanotechnology Initiative (NNI)

- Grand Challenge Report:
- Nanotechnology in Space Exploration
- addressing
- Nanomaterials
- Microspacecraft
- Micro-Nanorobotics
- Nano Sensors and Instrumentation
- Nano-Micro-Macro Integration
- Astronaut Health Management

- To download report, visit _[http://www.nano.gov](http://www.nano.gov/)__, follow links to report_

## Some examples of nanotechnology for

- mission insertion at NASA Ames

## What Do We Expect from a Well-Designed

- Sensor System?

- •	First, a single device has no value.  We need a system consisting of:
- 			-	Sensor or sensor array
- 			-	Preconcentrator (almost always needed)
- 			-	Micropump?  Microfan?
- 			-	Sample handling, delivery, fluidics
- 			-	Signal processing unit
- 			-	Readout unit (data acquisition, processing, storage)
- 			-	Interface control I/O
- 			-	Integration of the above
- •	Criteria for Selection/Performance
- 			-	Sensitivity (ppm to ppb)
- 			-	Absolute discrimination
- 			-	Small package (size, mass)
- 			-	Low power consumption
- 			-	Rugged, reliable
- 			-	Preferably, a technology that is adaptable to different platforms
- 			-	Amenable for sensor network or sensor web when needed

## Why Nanomaterials/Nanosensors?

- •	Compared to existing systems, potential exists to improve sensitivity limits, 		and certainly size and power needs
- •	Why?  Nanomaterials have a large surface area.  Example: 	SWCNTs have a 		surface area ~1600 m2/gm which translates to the size of a football field for 		only 4 gm.
- •	Large surface area           large adsorption rates for
- 	gases and vapors          	changes some measurable
- 	properties of the nanomaterial           basis for
- 	sensing
- 		-	Dielectric
- 		-	Capacitance
- 		-	Conductance
- 		-	Deflection of a cantilever
- 		-
- 		-

- 4 grams

## Various Carbon Nanostructures

- •	Single-walled carbon nanotubes (SWCNTs)
- 		-	Either a single tube or a film used in the
- 			device
- 		-	Vapor or gas adsorption on the material
- 			leading to a measurable property change
- 		-	Multiwalled carbon nanotubes (MWCNTs) may not be as good
- •	Vertically Oriented Carbon Nanofibers (CNFs)
- 		-	Multiwalled carbon nanofibers
- 		-	Walls are not parallel, instead bamboo-like
- 		-	Individual, free-standing, vertical
- 		-	Function as nanoelectrode, support a probe
- 			molecule at the tip amenable for interaction
- 			with target
- 		-	Nanoelectrode array

## Conductivity Change of CNTs Upon

- Gas/Vapor Adsorption

- •	Early chemical sensors were of the CHEMFET type with SnO2
- 	and other oxide conducting channels
- •	Similar CNT-FETs have been tested in the literature, exposing to 	NH3, NO2, etc.; change in conductivity has been observed
- •	Limitations of CNT-FET
- 		-	Single SWCNT is hard to transfer or grow *in situ*
- 		-	Even a film of SWCNTs by controlled deposition in the 				channel is complex
- 		-	3-terminal device is complex
- 			to fabricate
- 		-	Commercial sensor market is very
- 			cost sensitive

## NASA Ames Alternative to CNT-FET:

- •	Conventional thin film transistor approach is complex and expensive
- •	Two terminal chemiresistor is cheaper, easier to fabricate
- 		1.	Interdigitated electrode device using **simple microfabrication**
- 		2.	Disperse purified SWCNTs in DMF
- 		3.	Solution casting of SWCNTs across the electrodes

- Jing Li et al., Nano Lett., **3**, 929 (2003); Y. Lu et al., Chem. Phys. Lett., Vol. 391, p. 344 (2004).

- Interdigitated Chemiresistor

## Nanosensing Technology

**Using pattern matching algorithms, the data is converted into a unique response pattern**

_**Operation**_**:**
**The relative change of current or resistance is correlated to the concentration of analyte.**
**Array device “learns” the response pattern in the *****training***** mode.**
**Unknowns are then classified in the *****identification***** mode.**

## Scalable Array Approach

**•****	****12 to 36 sensing elements are on a chip (1cm x 1cm) now with heaters and thermistors.**
**•****	****Number of sensing elements can be increased on a chip.**
**•****	****Number of chips can be increased on a 4” wafer.**
**•****	****Wafer size can be increased to 6”, 8”, or 12”.**
**•****	****SWCNT solution-casting by ink jetting or using microarrays**

- (Multi-channel Sensing Chip)

## Sensitivity is the slope of the calibration curves. The average slope is 0.034+0.002 (6%).

## Nitrotoluene

- Sensing Mechanisms

## Analytes Tested and Selectivity Issues

**•****	****Functionalization of CNTs**
**•****	****CNT + polymer composites**
**•****	****Doping:  catalytic metal clusters**
**•****	****Field effect: gate bias for selective detection        **
**•****	****Programmed temperature control**
**•****	****Sensor array with pattern recognition: **
**	****electronic nose**
**•****	****Combination of the above**

- _Analytes Tested_
- •	NO2
- •	NH3
- •	CH4
- •	SO2
- •	Cl2
- •	HCl
- •	Acetone
- •	Benzene
- •	Toulene
- •	Nitrotoulene
- •	Hydrogen Peroxide
- •	Formaldehyde

## Flight Demo Unit for Satellite

- 32-channel sensor chip

- Ceramic chip carrier

- U.S. Navy Flight in 2007

***Sensing module ***
- Collection/integration of multiple sensor input
- Sampling system
- Data storage and transmission
- RS-422 connection

## Carbon nanotube based sensor combined with microelectronics and microfluidics for a complete system to meet mission needs.

**Biosensor for *****in situ***** life detection, CEV water quality monitoring, biomedical applications**

- Nano Biosensors for NASA Missions

- PI: Jun Li

- Team members: Alan Cassell, Hua Chen, Barbara Nguyen, and Jessica Koehne

## Nanoelectrode Array for Biosensors

## Nanoelectrode Array (NEA)

-  Each electrode is well separated with the neighbors (> 6R) so that the NEA behaves similar to a single NE.
-  Can further create an individually addressed multiplex array in an array-in-array format

- Challenges:
- Reliable fabrication techniques with affordable cost, particularly for low-density NEAs.

## Commonly Used Carbon Electrodes

## Macroelectrode vs. Nanoelectrode

- Semi-infinite planar linear diffusion

- Semi-infinite hemispherical diffusion

- Nanoelectrode Array

- * High sensitivity
- * Easily measurable signal
- * Fast detection

- glassy carbon

- I total = Iplanar + Iradial

- When reducing the size (r), orders of magnitude improvements are found in:
- 	(1) Spatial resolution: defined by r
- 	(3)* *Temporal resolution:* **Cell time constant* = RuCd = r Cd0/4
- 	(2) Sensitivity: signal-to-noise ratio: is/in  nFC0D0/r

## Nanoelectrode Array Fabrication

- 30 dies on a 4” Si wafer

- Embedded CNT Array after planarization

## Carbon Nanotube Electrodes 

- CNT coverage: ~ 20%
- 	(~3.0x109  CNTs/cm2)
- Average nearest-neighbor distance:
- 	~300 nm

- CNT coverage: < 1%
- 	(~1x108 CNTs/cm2)
- Average nearest-neighbor distance:
- 	> 1500 nm

- J. Li, H. T. Ng, A. Cassell, W. Fan, H. Chen, Q. Ye, J. Koehne, J. Han, M. Meyyappan,  *Nano. Lett.*, 2003, **3 **(5), 597.

- CV in 1mM K4Fe(CN)6 in 1M KCl at 20 mV/s

- Carbon Nanotube Electrodes
- at Different Densities

## Electrochemical Detection

- by AC Voltametry

## Nanotube Materials for 

- Nanotube Materials for
- Hubble Space Telescope (HST)

**Current Problem:**
**Hubble Space Telescope Imaging Spectrograph overheats, causing data degration**
**Solution:**
**Carbon Nanotube (CNT) as thermal interface greatly improves HST’s ability to dissipate excess heat**
**This technology has been licensed to industry for**
**computer chip cooling.**

- PI: Alan Cassell; Team Members: Jun Li, Brett Cruden, and Quoc Ngo

## Nanotechnology in CEV Development

- Metal catalyst
- Particles (Rhodium)

- Environmental management of
- contaminants during long duration space flight
**Carbon nanotubes have**
**large surface area**

- Jun Li, Alan Cassell, Metin Setti (CMU)

- Jim Arnold, Deepak Srivastava, Mairead Stackpoole

- PI: Jing Li

## •	Advances in thermoelectric cooling and power generation rely on 	the ability to increase the thermoelectric figure-of-merit ZT to 3 		and above.

- •	Inorganic nanowire arrays of bismuth
- 	telluride, indium antimonide offer
- 	potential to meet this goal.
- _Applications_
- 	-	Power supplies for robots, rovers,
- 		CEV, human habitats
- 	-	Efficient coolers for electronics,
- 		lasers and detectors
- 	-	Waste heat recovery

- Thermoelectric Refrigeration

- PI: Laura Ye; Modeling: Natalio Mingo

## Novel nanomaterials
Such as inorganic nanowires (Si, Ge, oxides, nitrides
Next-generation rad-hard devices
-	Logic, memory devices
-	Optoelectronics: UV and IR detectors, 		nanolasers for astronomy
-	General requirements: low power, high 		performance, ultrasmall, rad-hard
Highly integrated smart nanosystems
-	Integration of computing technology with 		on-chip embedded functionalities 
•	Sensing, photonics, ...

- Such as inorganic nanowires (Si, Ge, oxides, nitrides
**Next-generation rad-hard devices**
- -	Logic, memory devices
- -	Optoelectronics: UV and IR detectors, 		nanolasers for astronomy
- -	General requirements: low power, high 		performance, ultrasmall, rad-hard
**Highly integrated smart nanosystems**
- -	Integration of computing technology with 		on-chip embedded functionalities
- •	Sensing, photonics, ...

***Sensing*****  **

***Information***
***storage ****** ***

***Information ***
***processing*****  **

- PI: Bin Yu, Cun Zheng Ning

- Radiation-hard Nanodevices

- Novel Vertical Transistor

- Novel architecture

- Integrated Logic-Memory-Sensing
- “Brain-like” system

## Carbon Nanotube Field Emitters

- X-ray diffraction/fluorescence (XRD/XRF) instrument, for quantitative mineralogy analysis of planetary surfaces (1 liter, 1 kg, 5 watts).

- Miniature carbon nanotube field emission X-ray tube

- For Spacecraft Instruments

- David Blake, Cattien Nguyen, Bob Espinosa

## Structure of CNT Field Emitters

- •	Nature of nanotubes (SWNTs, MWNTs, CNFs...)
- •	Clean emitting sites vs. adsorbates (water vapor, oxygen...)
- •	Microstructure
- •	Screening effect
- •	Diode vs. triode

- High voltage required and/or gap needs to be adjusted

- Current is controlled by gate voltage, independent of acceleration voltage

## Carbon Nanotube Field Emission

- Silicon and metal substrates
- Film, arrays

- Optimum type of CNT?
- Optimum CNT/substrate attachment?
- Optimum site density?

- CNT emitter fabrication
-  NASA Ames

- Field emission characterization
-  NASA Ames

- Integration in miniature X-ray tube
- (Oxford XTG Inc.)

- Various types of emitters were studied

## Nanotechnology in Civilian Aeronautics

- •	High strength/low weight nanocomposites, coatings and other 		nanomaterials for:
- 		-	Load-bearing structures
- 		-	Lightning protection
- 		-	EMI protection
- 		-	Adhesives, quick repair kits
- 		-	Quick cleaning of wings
- 		-	Sensors
- 		-	Light weight, high efficiency power sources
- •	Intelligent computational materials design

- Computational material science will play the critical role in early 21st Century just as what Computational Fluid Dynamics did for aircraft industry in late 20th century.