Film Bulk Acoustic Resonator-based Ultra-Sensitive Biosensor Array Using Low Cost Piezoelectric Polymer as the Active Material

Lead Research Organisation: University of Bolton
Department Name: Centre for Materials Res and Innovation

Abstract

Biosensors are a type of microdevices that are able to measure very small concentration of biological molecules or chemical substances through specific bio-binding or chemical absorption. Biosensors are extremely useful in diagnosis, fighting terrorist and prevention of pandemic disease spread. Through detection of associated molecules such as DNA and antibody-antigen, they are very promising in early diagnosis of cancers and genetic disorder. Widespread applications of thus biosensors will lead to fast and accurate diagnosis, thus preventing unnecessary mortality and saving thousands of lives. Deployment of biosensors at key public locations enables detection of disease or biological substances in time, preventing spread of diseases or biochemical attach. High quality biosensors must be very sensitive, easy to use, low cost and fast with integrated electronics. Also multi-detection of many molecules using arrays is essential for reliable diagnosis and detection. Although many technologies have been developed such as microarrays and label-free electrochemical and optical biosensors. they have various shortages: lack of sensitivity and resolution, bulky and precise control of the sample position, or a large device size and lack of scalability etc. A multi-disciplinary team from Universities of Cambridge (CU), University of Manchester (MU) and University of Bolton (BU) is formed to develop a technology platform for biochemical detection using the most advanced film bulk acoustic wave resonator (FBAR) technology. FBAR device has a structure similar to quartz crystal microbalance but with a submicrometer thick piezoelectric (PE) active layer. It consists of a thin PE-layer with electrodes on both sides. Application of A.C. signals generates a standing wave between the two electrodes through PE effect. The resonant frequency is extremely sensitive to mass attached on the electrode surface owing to small device dimensions (thus the small base mass) and high operating frequency. Extremely small concentration of biomolecules can be detected through specific bio-binding with pre-deposited probe molecules on the electrode surface. The device has the combined merits of all other biosensors: label-free, ultra-high sensitivity and low detection limit, small dimensions, suitability for multi-detection using FBAR arrays, electronic output signal and low cost. The project will initially focus on development of high performance FBARs using piezoelectric (PE) ZnO thin films owing to its relatively mature technology. Biosensing technology will be developed in parallel using prostate-specific antigens (PSA) and peptide aptamers that specifically bind to those PSAs. Peptide aptamers have much better stability and specificity than proteins. Development of ZnO-based FBAR biosensors enables us to clarify all issues in device modelling, fabrication and characterisation, immobilization and biodetection etc. At the second stage, the project will develop novel FBARs on glass and plastic substrates using low cost PE-polymers. PE polymers such as polyvinylidene fluoride (PVDF) and its copolymer PVDF/TrFE have a piezoelectric constant and coupling coefficient comparable to the piezoelectric ceramics, and are biocompatible and chemically inert. Owing to their flexibility, it allows fabrication on low cost glass and plastic substrates. The cost of these biosensors will be extremely low. BU has excellent facilities for modelling and design, and for material and device characterisation. They will be responsible for modelling, design and characterisation. CU has a world-class cleanroom housed with excellent deposition, etch and microfabrication facilities. They will offer the expertise and experiences in device fabrication. The MU has first class biolab environment and relevant facilities for biological research. They are experts in protein adsorption, interfacial conformation, structural unfolding, and synthesis and cloning of peptide aptamers.

Publications

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Ashley G (2010) Chemically Sensitized Thin-Film Bulk Acoustic Wave Resonators as Humidity Sensors in Journal of The Electrochemical Society

 
Description 1_Developed a unique process to deposit piezoelectric thin films by using a novel HiTUS sputtering deposition technology. ZnO thin films have extremely low stress and defect density which can be used for fabrication processing directly without need for further annealing to reduce the stress. The process has a great potential for application in electronics industrial and material science as it produces thin films with very high quality of crystallinity and electronics properties.

2_Developed a scalable process for fabricating high quality FBAR devices with high yield, and can be transferable to industry. The resonant frequency of FBARs with ZnO piezoelectric active layer is in the range of 1.5-3GHz and the quality factors of FBARs are over 1000, among the best values achieved. These FBAR devices are not just useful for sensors, but also can be used for high frequency resonators for next generation mobile and wireless communications applications.

3_Developed a new type of FBAR devices with carbon nanotube (CNTs) as the top electrode for the first time. This type of devices have significantly improved performance owing to the extremely high acoustic impedance and elastic modulus of CNTs layer, the reduced mass of the CNT electrodes (compared with metal) and the suppression of surface travelling waves, resulting in enhanced Q-factor over 2000, the best values reported.

4_Developed a software to continuously track the frequency of FBARs with a capability to filter out all noise round a resonant peak and extract the accurate resonant frequency, hence the frequency shift induced by the mass loading effect. It has been proven to be the most effective and efficient piece of software for acoustic wave resonators applications.

5_Demonstrated that FBARs can be temperature, pressure, humidity and UV-light sensors with high sensitivity, and also are excellent gas phase biosensors for detecting traces of biomolecules and odors with detection limitation down to 10-13g, with possibility for 10-15g.

6_Developed a unique UV-light assisted sputtering deposition method to deposit AlN thin films at room temperature with controllable crystal orientation and quality. This technique will have significant impact to the industry for deposition of hard ceramic thin films which typically need high substrate temperatures for deposition.

7_Developed a method to extract accurate intrinsic parameters for FBARs which can be used for better circuit design and applications, and an analytic model for FBARs with high electromechanical coupling coefficient, so that FBAR models can be used for accurate circuit design and applications in circuits.
Exploitation Route Potential uses of the outcome of the project are in the following areas:

1. High quality factor FBARs with high frequency can not only be used for sensors, but also they can be used as high frequency resonators for the development of next generation mobile and wireless communications. The market for these applications is much larger than the sensors in next 5-10years as every communication device requires several resonators for oscillators, filters etc.

2. The FBAR-based physical sensors (Temperature, humidity, pressure and UV-light), and gas phase based biological and odor sensors will have great potential for practical applications in engineering, healthcare, remote sensing and monitoring etc. FBARs are small in size, and made on thin film, thus, they can be simply integrated with electronics to form detection system. Array of FBARs can be used for multi-sensing in parallel with self-temperature referenced.

3. The method to extract accurate intrinsic parameters of FBARs with different size, and the accurate equivalent circuit (analytical model) for FBARs can be used for circuit design and modeling with better results and accuracy, thus could significantly reduce the development time and cost.

4. The UV-light assisted sputtering process would be very useful for industry for depositing high quality hard ceramics with lowing substrate temperature substantially. Generally, hard ceramics are difficult to deposit by sputtering, needing elevated substrate temperature or high plasma power to assist reaction. Use of UV-light has been proven to be effective and efficient in lowering the deposition temperature, yet achieving thin films with high crystallinity and controllable orientations.
We found that FBARs with ZnO on SiO2 membrane have two well defined resonant peaks, and they have different ways respond to temperature change, one has a positive temperature coefficient of frequency (TCF), one has a negative TCF. This can be utilized as a self-temperature reference, eliminating the need for additional temperature sensors for calibration. This has been explored for a patent (in the filing process), and has been explored for applications in sensing. We have discussed this application with a number of companies for commercial use.
Sectors Communities and Social Services/Policy,Electronics,Environment,Healthcare

 
Description The technologies developed through this project have been the foundation for our recent advanced technologies of flexible surface acoustic wave (SAW) and FBAR, and their sensors on arbitrary substrates that will provide unique techniques for flexible, wearable electronics. Also, the dual-mode frequencies FBAR sensing technology has been exploited applications in industries and healthcare such as automotive and microelectronics as highly sensitive sensors for thickness monitoring and cancer detection. Additional funding (£~80k) has been obtained from Cambridge enterprise to study its feasibility for these applications. Further funding may be obtained for this to be applied for prostate-cancer detection.
First Year Of Impact 2015
Sector Electronics,Healthcare,Manufacturing, including Industrial Biotechology
Impact Types Economic

 
Description Feasibility study of high temperature SAW sensors
Amount £3,000 (GBP)
Funding ID RR0001 
Organisation Rolls Royce Group Plc 
Sector Private
Country United Kingdom
Start 10/2010 
End 02/2011
 
Description High Temperature Advanced Sensor System for Aircraft Engine Health Monitoring
Amount £15,000 (GBP)
Funding ID RR0002 
Organisation Rolls Royce Group Plc 
Sector Private
Country United Kingdom
Start 10/2011 
End 04/2012
 
Description Leverhulme Trust
Amount £97,186 (GBP)
Funding ID F/01 431/C 
Organisation The Leverhulme Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 11/2009 
End 12/2012
 
Description Rolls-Royce Plc
Amount £18,000 (GBP)
Funding ID RR0002 
Organisation Rolls Royce Group Plc 
Sector Private
Country United Kingdom
Start 10/2011 
End 04/2012
 
Description Rolls-Royce Plc
Amount £3,000 (GBP)
Funding ID RR0001 
Organisation Rolls Royce Group Plc 
Sector Private
Country United Kingdom
Start 07/2010 
End 12/2011
 
Description Royal Society of London
Amount £11,000 (GBP)
Funding ID JP090873 
Organisation The Royal Society 
Sector Charity/Non Profit
Country United Kingdom
Start 06/2011 
End 07/2012
 
Description Development of high performance FBARs for electronics and sensors 
Organisation Zhejiang University
Country China 
Sector Academic/University 
PI Contribution We have worked together for three years to develop a number of technologies, including extracting accurate intrinsic parameters of FBARs with high coupling coefficient, analytic models for FBARs, unique UV-light assisted sputtering method for depositing AlN at room temperature. We have published 6 joint papers in journals.
Start Year 2010
 
Description Development of high quality piezoelectric materials for SAW-based microfluidics 
Organisation University of the West of Scotland
Country United Kingdom 
Sector Academic/University 
PI Contribution We have built up a number of activities to develop ZnO, AlN piezoelectric thin films for FBARs and SAW devices fabrication, and SAW-based microfluidcs development. We have jointly published 6 journal papers
Start Year 2010
 
Title Continuous ZnO film growth 
Description describe methods to synthesize ZnO films with embedded ZnO nanorods, which has high piezoelectric constant than bulk ZnO materials 
IP Reference GB2469869 
Protection Patent application published
Year Protection Granted
Licensed No