Development of a Miniaturized Electromechanical Biosensing Platform

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The objective of this project is to develop a miniaturized, low cost, and high throughput biosensing technology that can be applied to a wide range of applications in medical diagnosis and biomedical research. U.S. health care spending is dramatically high and growing, making the ballooning cost of healthcare a major challenge for the nation. Affordable and ubiquitous screening technologies allowing frequent testing for early diagnosis of diseases are effective preventive methods to reduce health care cost. The proposed effort can pave the way towards low-cost sensors with simple and rapid sensing procedures for home based monitoring of regular bodily functions/parameters, and point-of-care diagnosis of more complex disorders. Furthermore, performing such research in an academic environment has the added advantage of training a few highly skilled engineers that can have significant contributions to the industry over the course of their career. Expertise in micro, nano and biomedical science and engineering is in high demand in the current high-tech US economy. Two full-time PhD students and up to three undergraduate researchers will be educated and involved in the proposed research and development activities. To promote diversity, efforts will be devoted to recruitment of highly qualified students from under-represented and minority groups to be involved in the activities. This project will also allow the investigators to enrich and invigorate their ongoing micro/nanotechnology educational and outreach programs by producing valuable new knowledge and interesting material for courses, lab tours, and demos.The proposed biosensing platform utilizes micro to nanoscale electromechanical resonators as highly sensitive mass sensors capable of detecting and measuring adsorption of fractions of single molecular layers onto their surfaces. There have been significant advances in micro/nanoscale electromechanical resonator technologies over the past two decades, mainly driven by applications of such devices as frequency references and filtering elements in electronics. With dimensions in the lower to submicron range, such devices can have mass sensitivities in the pico-gram to femto-gram range for microscale, and down to atto-grams and below for nanoscale resonators. This is several orders of magnitude better than that of conventional quartz crystal microbalances (QCM). High-resolution biomolecular sensors can be realized by covering the surface of such devices with a self-assembled monolayer of a selective molecular recognition element (MRE). However, despite their tremendous potential, utilization of Micro/Nano-mechanical resonators in biosensing applications remains almost non-existent. This is mainly due to the major bottleneck of operating such devices in contact with liquid media, where almost all biosensing activity takes place. Due to their small dimensions and consequently large surface area to volume ratio, the quality factor (Q) of such resonators drops significantly when immersed in liquid to the point that their resonance response completely disappears. Under this project, a comprehensive multi-faceted effort will be launched to further enhance MEMS resonator performances in contact with biological solutions and address some of the associated challenges for development of a general purpose biosensor array technology that can be applied to a wide variety of sensing applications. A new micromechanical structure is proposed, comprising of a piezoelectric resonator fabricated on a thin membrane with a backside reaction cavity where the molecular bonding to the membrane occurs. The membrane isolates the resonator and electrical signals required for its operation from the biological sample in order to achieve optimal performance for the device in contact with liquid.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.