Purdue Zero Gravity Microcantilever Project
The Project
Background
Deep space exploration will require new and reliable sensors capable of monitoring gas-phase contaminants in the space craft as well as astronaut health. Viable sensors for deep-space must posses a rapid and sensitive transduction scheme. In addition, they must be light weight and require low power. An emerging sensor platform that satisfies these requirements are micro-cantilever arrays. Microcantilever arrays are chemically functionalized (coated) micromechanical sensors being used to detect airborne and fluid borne analytes in the sub-picogram range. These arrays are being studied at Purdue under the auspices of the NASA funded Institute for Nanoelectronics and Computing (INAC).
Micro-machined cantilevers have been developed as sensitive transducers in many micro/nano-mechanical sensors. Cantilevers can be microfabricated by standard low-cost silicon technology and by virtue of the size achievable, are extremely sensitive. They provide label-free, real-time measurements in fluids and/or air in a single-step reaction without the sample manipulation required in traditional diagnostic systems such as ELISA (Enzyme-linked Immunosorbent Assay), oligonucleotide (DNA or RNA) hybridization capture, PCR (Polymerase chain reaction) and fluorescence based techniques.
Cantilevers can also be batch fabricated, leading to a decrease in production costs and allowing the possibility of integrating multiple functional devices onto the same platform, i.e. moving towards proverbial goal of a “lab-on-a-chip”. They can also be fabricated into arrays, permitting autonomous detection of multiple analytes in a single step and accommodating a built-in internal reference sensor essential for biospecific detection.
To be useful as sensors, a microcantilever must be first functionalized with an appropriate chemistry to selectively bind a target analyte. The functionalization could range from a thin polymer coating applied to one side of the cantilever for gas phase detection to evaporated thin films that are then selectively functionalized by appropriate chemistry. In all cases, the cantilever preparation is done well in advance, utilizing a variety of diagnostic techniques and the prepared cantilever chips are then inserted into a sensor platform which consist of a flow cell and a means to sensitively detect either static cantilever deflection or dynamic change in the resonant frequency.
An advantage of the microcantilever array is their small size and versatility. They can be mounted unobtrusively throughout the space craft cabin to continuously monitor air quality while others could be used on a daily basis to monitor astronaut fluids for health purposes.
Recent publications have reported the feasibility of using microcantilevers as versatile sensors. Microcantilevers have been used to detect E.coli, to distinguish between DNA oligonucleotides, to measure pH changes, to measure surface stress associated with protein and antigen-antibody binding in liquid phase, to identify analyte vapors in gases and as cancer markers. The capture of larger entities such as cells on antibodies/peptides attached to cantilevers has not been reported using the stress detection method. However, detection of cells and microorganisms like E.Coli and Listeria has been demonstrated using a mass detection method that yields a shift in resonant frequency of a cantilever.
Abstract
Functionalized piezoresistive microcantilever arrays form a light-weight and sensitive platform to detect multiple target analytes for monitoring contaminants and astronaut health in space flight. We propose to test microcantilever arrays under zero-g conditions to better learn what, if any, limitations zero-g might impose on future microcantilever-based detection schemes for both gas phase and liquid phase monitoring.
Schedule
| Flight Physical: | May 1, 2006 |
|---|---|
| PIF, Signature Form:: | June 7, 2006 |
| TEDP: | June 21, 2006 |
| Evacuation plans/Badging requests/Dinner RSVP: | July 19, 2006 |
| Flight: | August 3, 2006-August 12, 2006 |
| Final Report: | October 6, 2006 |