Integrated Smart Nanosensors for Space Biotechnology Applications

1. Integrated Smart Nanosensors for Space Biotechnology Applications Toshikazu Nishida Mark E. Law University of Florida NASA Research Briefing September 25, 2002

2. Introduction • Overview of the Program • Test Bed Development • Miniaturization of Macro Sensors • Nanosensor Development • Equipment • Summary and Conclusions

3. Overview • Goal: Develop Low Mass, Low Power Sensors • Interdisciplinary Work • ECE, MSE, Aerospace, Chemical, Civil, Environmental Involved • Miniaturize Macroscopic Sensors • New Applications for NEM’s Devices

4. Technical Outline • Test Bed Development • Water Purification Mazyck(Environmental) • Miniaturization of Macro Sensors • Cumulative Flow Hatfield(Civil), Annable(Environmental) • Gas Sensor Wachsmann (MSE) • Nanosensor Development • Flow Sensor Sheplak(Aero) and Nishida (ECE) • Wide Band gap Sensors Ren (Chem), Chauhan(Chem), Pearton(MSE) • Membrane Development Jones(MSE), Law(ECE) • Self-Powered Sensors Nishida(ECE), Sheplak(Aero)

5. Integration of Intelligent Sensors for Water Recovery • David W. Mazyck, Environmental Engineering Sciences • Technical Leader for Water Recovery • NASA ES CSTC • Objective has been to design a micro-gravity compatible reactor that removes or destroys organics from recycled water • Two systems currently under development • Magnetically Agitated Photocatalytic Reactor • MAPR sponsored by the ES CSTC • In-situ Regenerated Activated Carbon • IRAC to be presented at 2002 ICES

6. Project Description • MAPR • Magnetic particles are coated with silica and TiO2 to photocatalytically degrade organics • Magnetic field fluidizes particles to enhance mixing and destruction rates • IRAC • Capture organics through traditional adsorption with TiO2 coated activated carbon • In-situ regenerate carbon once exhausted with UV light

7. Research Description • Optimize MAPR for the destruction of target organics • Improve IRAC regeneration efficiency • Integrate sensors to monitor or control flow, temperature, and specific organics • Coupled to Fluidic Sensing, Flow Sensors, Cumulative Flow Sensor, Membrane Development

8. Time-Controlled Sensor Particle Retrieval Power Control through Sensor N-S MAPR Raman Analyzer N-S Water In UV Lamp N-S Smart Photocatalytic Magnetic Particle UV Regenerator Chemical/Biological pollutant Smart Regenerative Sensing System Smart Sensor particle System Schematic NEMs Flow Sensor Integrated Treatment and Sensing System for Water Purification in Space (MAPR and IRAC interchangeable).

9. Cumulative Flux Sensor • Kirk Hatfield, Civil Engineering • Mike Annable, Environmental Engineering Sciences • Objective is to miniaturize working system for pollutants

10. Cumulative Contaminant Flux • Contaminants in the flow, q are intercepted and retained on the sensor. • The mass of contaminant retained, Mc is used to quantify cumulative contaminant mass flux, Jc Porous Flux meter Dye intercepted in a flux meter Contaminant Intercepted

11. Cumulative Water Flux • The flow field leaches a resident tracer from the sensor • The mass of tracer remaining, Mr is used to calculate cumulative water flux, q over exposure period, t ResidentTracer Porous Flux meter

12. Gas Sensor • Eric Wachsmann, Materials Science • Objective to develop a Miniature Low-Power Integrated CO/CO2/H2/H2O/O2 Sensor for Space Biotechnology Applications

13. Gas Sensor • Simple potentiometric sensor is not limited to a specific size and does not require separate reference atmosphere • We have already demonstrated approach provides ppm sensitivity for CO and NO and selectivity for NO • We will determine selectivity for CO • We will determine scalability toward nano-dimensions • In future phase we will produce miniature CO/CO2/O2/H2/H2O sensor

14. MEMS Sensors for Environmental Systems • Dr. Mark Sheplak (Mechanical and Aerospace Engineering) • Dr. Toshi Nishida (Electrical and Computer Engineering) • Objective • Instrumentation-grade MEMS sensors for environmental systems • Specifically, MEMS flow sensors for water recovery reactors in collaboration with David Mazyk in Environmental Engineering • Current Technology • Macroscopic liquid flow sensors • Turbine • Vane • Piston • Why MEMS Flow Sensor? • Smaller weight, size, power • Reduced pressure drop

15. MEMS Sensors for Environmental Systems Flow • Floating Element Flow Sensor • Direct detection of flow from imparted shear force on floating element • Flush mounted in fluidic channel wall for minimal pressure drop • Designable for low or high flow rate by adjusting spring force (tethers) • Detection Method for Displacement of Floating Element • Optical Moirè fringe detected via CCD Figure 1 - Floating Element Principle Flow Bottom Top Moirè fringe Figure 2 - Physical Structure

16. Wide Band Gap Semiconductor Based Sensors Fan Ren, Chemical Engineering Anuj Chauhan, Chemical Engineering Steve Pearton, Materials Science and Engineering Objectives Fabricate different semiconductor SiC and GaN based electronic devices to investigate the detection limit Lateral electric fields can be used to separate charged molecules as they flow through a micro/nano fluidic channel.

17. SiC and GaN based materials are chemically and thermally stable and suitable for high temperature and harsh environment applications Electronic devices from SiC and GaN are highly sensitive to several gases including hydrogen, carbon mono-oxide and hydrocarbons Background

18. SiC Schottky Diode Based Gas Sensor

19. Schematic of Microfluidic Device Fluid inlet Detector 2 mm Fluid outlet 2 mm 2 cm electrodes The electric field concentrates the charged molecules near the wall, where they slow down due to the smaller velocities near the wall. The molecules with smaller diffusion coefficient, i.e., the larger molecules concentrate more near the walls, and thus slow down more. This leads to separation of molecules of different sizes. Pulse introduced at time=0 1 Pulses at different time 0.8 Concentration 0.6 0.4 0.2 0 0 Axial Position

20. Membrane Sensor Development • Kevin S. Jones, Materials Science Engineering • Mark E. Law, Electrical and Computer Engineering • Objective is to develop a single crystal silicon membrane for use in pressure and mass sensors - offer greater reliability and lower noise

21. Membrane Sensor Development Single Crystal Membrane Development • Operational Capability: • Single Crystal silicon membranes for use as both • Integrated Pressure Sensors and • Integrated Mechanical Resonators • Improved piezo-transducer formation through the use of Ultra-low Energy Ion Implantation and Laser Thermal Processing • Estimated Improvement in Dynamic range of 32 to 160 dB • Estimate a 10X reduction in the noise floor over bonded and etched back MEMS acoustic sensors • Significant long term resonator stability improvement because of the lack of grain creep Silicon etching and anneal can lead to membrane Single Crystal membrane 0.75 µm thick Cavity 0.27mm2 in area Proposed Technical Approach: Develop the “Empty Space in Silicon” (ESS) process utilizing focused ion beam etching and reactive ion etching to produce etched holes in single crystal Si Utilize high temperature annealing in a reducing ambient to flow the silicon over the etched features creating single crystal membranes Develop ultra shallow junction formation methods using plasma assisted doping on ESS materials for piezoresistive transducers formation

22. Self-Powered Monitoring of Life Support Systems • Principal Investigators • Dr. Toshi Nishida (Electrical and Computer Engineering) • Dr. Khai Ngo (Electrical and Computer Engineering) • Dr. Mark Sheplak (Mechanical and Aerospace Engineering) • Dr. Lou Cattafesta (Mechanical and Aerospace Engineering) • Dr. Jean Andino (Environmental Engineering Sciences) • Motivation • Flexible deployment of sensors to monitor health of life support systems requires self-powered wireless sensors • Target • To design a MEMS vibrational energy harvesting device that enables a self-powered sensor and wireless transmitter for ambient air monitoring and revitalization

23. Self-Powered Monitoring of Life Support Systems • Approach • Cantilever structure with a compliant structural silicon/piezoelectric composite beam and an inertial mass at the tip • Design • Scaling analysis of output power with geometry, force, and material properties • Adaptive power circuitry to maximize power flow • Tasks • Detailed design of the MEMS vibrational micro-generator (Nishida, Cattafesta, Sheplak) • Power scaling for integration with electronics (Ngo, Nishida) • Design for insertion into existing ambient air monitoring and revitalization technologies (Andino)

24. Aligned Wafer-Bonding System • EVG 620 Double-Sided Lithography System: • +/- 0.5 mm front-to-backside wafer alignment and lithography for fabrication of nano- and micro-systems. • printing modes: such as soft, hard, vacuum contact and proximity are possible. • aligned wafer bond capabilities used for the fabrication of stacked layers in nano- and micro-systems. • EVG 501 Aligner Capabilities: • precision wafer to wafer alignment processes for silicon-direct, anodic, thermo-compression and pressure bonding. Precision aligned wafer bonder (EVG 620 / EVG 501)

25. Connections • Flow Sensor - Water Purification • Cumulative Sensors with Membrane MEM’s and Water Purification • Potentiometric sensing with wideband gap materials • Self-Power Sensor with Membrane Development • Self-Power with all sensor technologies

26. Major 18 month Objectives • Optimize Water Purification System with Integrated Sensors • Miniaturize Cumulative Flow and Contaminant Sensor • Miniature Low-Power Integrated CO/CO2/H2/H2O/O2 Sensor • Demonstrate MEM’s flow sensor in Water Purification Systems • Develop Wideband gap materials for sensing applications • Develop Novel Single Crystal Membrane Technology for MEM’s • Demonstrate Self-Powered Sensor

27. Conclusions • Leveraged work offers more immediate payback • Seed grants are looking are possible “revolutionary” technologies - long term payoff • Good cross linking between tasks - we aim for a real coordinated activity