Robust Piezoelectric-Excited Millimeter-sized Cantilever Sensors for Detecting Pathogens in Drinking Water at 1 cell/LiterEPA Grant Number: R833007
Title: Robust Piezoelectric-Excited Millimeter-sized Cantilever Sensors for Detecting Pathogens in Drinking Water at 1 cell/Liter
Investigators: Mutharasan, R.
Institution: Drexel University
EPA Project Officer: Klieforth, Barbara I
Project Period: October 1, 2006 through September 30, 2009 (Extended to August 31, 2011)
Project Amount: $562,215
RFA: Development and Evaluation of Innovative Approaches for the Quantitative Assessment of Pathogens in Drinking Water (2005) RFA Text | Recipients Lists
Research Category: Drinking Water , Nanotechnology , Water
The goal of proposed research is to develop antibody-immobilized piezoelectric-excited millimeter-sized mechanically robust cantilever (PEMC) sensors for detecting pathogenic agents (PA) such as Cryptosporidium and Giardia and others in drinking water system and source waters without a concentration or filtration step.
The project has three main objectives: (1) explore and establish experimentally piezoelectric-actuated millimeter-sized cantilever sensor suitable for detecting one pathogen in one liter of water using new cantilever oscillation and measurement modalities; (2) develop flow cell-PEMC sensor detection assembly for testing sample volumes of 10-100 liters and characterize response of sensor to samples containing known number of Cryptosporidium and Giardia; and (3) develop PEMC sensor for confirming pathogen identity by its DNA signature, immobilize known 38-mer oligo (Gene Bank: L16997), and use DNA extracted from PEMC collected cells to verify the identity of pathogen (Cryptosporidium).
We will fabricate PEMC sensors and chemically immobilize antibodies against Cryptosporidium and Giardia on sensor surface. Spiked samples of water with the pathogen in concentration range of 0.1 to 10 cells/L will be passed through the PEMC sensor and resonance frequency measured continuously. Binding of pathogen decreases resonance frequency quantitatively. New oscillation modes that show promise of higher sensitivity (one cell per mL) will be investigated. New flow cell will be developed for passing 10 Liters or larger amount for detection in 10 minutes. The sensor surface acts as a “filter” and, thus, after a sensing cycle, the attached cells will be released, DNA extracted, and then exposed to another PEMC sensor that has immobilized DNA sequence that is unique to Cryptosporidium. The reduction in resonance frequency will indicate a positive detection.
We have shown that mass change sensitivity of our current PEMC sensor is in the range of 10 – 100 picograms. Through the proposed innovation we expect to improve the sensitivity to 1 picogram. This will be accomplished through using new oscillation modality (twist or flex, or bending at 150 to 250 kHz). The novelty of the proposed modality of sensing is there is no filtration step and it is one-step sensing.