Acoustic Wave Based MEMS Devices, Development and Applications

Acoustic waves based MEMS devices offer a promising technology platform for a wide range of applications due to their high sensitivity and the capability to operate wirelessly. These devices utilize acoustic waves propagating through or on the surface of a piezoelectric material. An acoustic wave device typically consists of two layers, metal transducers on top of piezoelectric substrate or thin films. The piezoelectric material has inherent capabilities of generating acoustic waves related to the input electrical sinusoidal signals placed on the transducers. Using this characteristic, different transducer designs can be placed on top of the piezoelectric material to create acoustic wave based filters, resonators or sensors. Historically, acoustic wave devices have been and are still widely used in telecommunications industry, primarily in mobile cell phones and base stations. Surface Acoustic Wave (SAW) devices are capable of performing powerful signal processing and have been successfully functioning as filters, resonators and duplexers for the past 60 years. Although SAW devices are technological mature and have served the telecommunication industry for several decades, these devices are typically fabricated on piezoelectric substrates and are packaged as discrete components. Considering the wide flexibility and capabilities of the SAW device to form filters, resonators there has been motivation to integrate such devices on silicon substrates as demonstrated in (Nordin et al., 2007; M. J. Vellekoop et al., 1987; Visser et al., 1989). One such example is illustrated in (Nordin et al., 2007) where a CMOS SAW resonator was fabricated using 0.6 m AMIs CMOS technology process with additional MEMS post-processing. The traditional SAW structure of having the piezoelectric at the bottom was inverted. Instead, the IDTs were cleverly manufactured using standard complementary-metal-oxide-semiconductor (CMOS) process and the piezoelectric layer was placed on the top. Active circuitry can be placed adjacent to the CMOS resonator and can be connected using the integrated metal layers. A SAW device can also be designed to have a long propagation path between the input and output transducer. The propagating acoustic waves will then be very sensitive to ambient changes, allowing the device to act as a sensor. Any variations to the characteristics of the propagation path affect the velocity or amplitude of the wave. Important application for acoustic wave devices as sensors include torque and tire pressure sensors (Cullen et al., 1980; Cullen et al., 1975; Pohl et al., 1997), gas sensors (Levit et al., 2002; Nakamoto et al., 1996; Staples, 1999; Wohltjen et al., 1979), biosensors for medical applications (Andle et al., 1995; Ballantine et al., 1996; Cavic et al., 1999; Janshoff et al., 2000), and industrial and commercial applications (vapor, humidity, temperature, and mass sensors) (Bowers et al., 1991; Cheeke et al., 1996; Smith, 2001; N. J. Vellekoop et al., 1999; Vetelino et al., 1996; Weld et al., 1999). In recent years, the interest in the development of highly sensitive acoustic wave devices as biosensor platforms has grown. For biological applications the acoustic wave device is integrated in a microfluidic system and the sensing area is coated with a biospecific layer. When a bioanalyte interacts with this sensing layer, physical, chemical, and/or biochemical changes are produced. Typically, mass and viscosity changes of the biospecific layer can be detected by analyzing changes in the acoustic wave properties such as velocity, attenuation and resonant frequency of the sensor. An important advantage of the acoustic wave biosensors is simple electronic readout that characterizes these sensors. The measurement of the resonant frequency or time delay can be performed with high degree of precision using conventional electronics. This chapter is focused on two important applications of the acoustic-wave based MEMS devices; (1) biosensors and (2) telecommunications. For biological applications these devices are integrated in a microfluidic system and the sensing area is coated with a biospecific layer. When a bioanalyte interacts with this sensing layer, physical, chemical, and/or biochemical changes are produced. Typically, mass and viscosity changes of the biospecific layer can be detected by analyzing changes in the acoustic wave properties such as velocity, attenuation and resonant frequency of the sensor. An important advantage of the acoustic wave biosensors is simple electronic readout that characterizes these sensors. The measurement of the resonant frequency and time delay can be performed with high degree of precision using conventional electronics. Only few types of acoustic wave devices could be integrated in microfluidic systems without significant degradation of the quality factor. The acoustic wave based MEMS devices reported in the literature as biosensors are film bulk acoustic wave resonators (FBAR) and surface acoustic waves (SAW) resonators and SAW delay lines. Different approaches to the realization of FBARs and SAW resonators and SAW delay lines used for various biochemical applications are presented. Next, acoustic wave MEMS devices used in telecommunications applications are presented. Telecommunication devices have different requirements compared to sensors, where acoustic wave devices operating as a filter or resonator are expected to operate at high frequencies (GHz), have high quality factors and low insertion losses. Traditionally, SAW devices have been widely used in the telecommunications industry, however with advancement in lithographic techniques, FBARs are rapidly gaining popularity. FBARs have the advantage of meeting the stringent requirement of telecommunication industry of having Qs in the 10,000 range and silicon compatibility

A CMOS power splitter for 2,45 GHz ISM band RFID reader in 0,18 µm CMOS technology

Identifikacija radio frekvencije (RFID) je jedna od najbrže rastućih tehnologija uporabljiva u gotovo svakom sektoru za pohranu i bežično uzimanje podataka. Trenutni napredak u CMOS tehnologiji pomaže znanstvenicima i tehnolozima smanjiti dimenzije i poboljšati funkcionalnost RFID sklopova. U ovom radu ilustrirana je konstrukcija jednog RF-CMOS razdvajača snage električnog kruga u 0,18 µm Silterra RF-CMOS tehnologiji za 2,45 GHz RFID čitač. Wilkinsonov razdjelnik snage izabran je za predloženi razdvajač snage električnog kruga s induktorima i kondenzatorima na čipu. Predloženi razdvajač snage ostvaruje najveći gubitak zbog umetanja od 10 dB. AWR Microwave Office® koristi se za simulaciju električnog kruga i za određivanje njegovih S-parametara. Za konstruiranje induktora s točnim vrijednostima u 2,45 GHz rabljen je Sonnet® dok je Cadence® rabljen za razmještaj kondenzatora i otpornika.Radio frequency identification (RFID) is one of the most rapidly growing technologies to be utilized in almost every sector for storing and retrieving data wirelessly. Current advancements in CMOS technology help the scientists and technologists to reduce the size and improve the functionalities of the RFID circuits. In this paper, the design of an RF-CMOS power splitter circuit in 0,18 µm Silterra RF-CMOS technology is illustrated for a 2,45 GHz RFID reader. Wilkinson power divider is chosen for the proposed power splitter circuit with on-chip inductors and capacitors. The proposed power splitter achieves a maximum insertion loss of 10 dB. AWR Microwave Office® is used for the simulation of the circuit and for determination of its S-parameters. To design the inductors with accurate values in 2,45 GHz Sonnet® is used whereas Cadence® is used for capacitor and resistor layout

A CMOS power splitter for 2,45 GHz ISM band RFID reader in 0,18 µm CMOS technology

Identifikacija radio frekvencije (RFID) je jedna od najbrže rastućih tehnologija uporabljiva u gotovo svakom sektoru za pohranu i bežično uzimanje podataka. Trenutni napredak u CMOS tehnologiji pomaže znanstvenicima i tehnolozima smanjiti dimenzije i poboljšati funkcionalnost RFID sklopova. U ovom radu ilustrirana je konstrukcija jednog RF-CMOS razdvajača snage električnog kruga u 0,18 µm Silterra RF-CMOS tehnologiji za 2,45 GHz RFID čitač. Wilkinsonov razdjelnik snage izabran je za predloženi razdvajač snage električnog kruga s induktorima i kondenzatorima na čipu. Predloženi razdvajač snage ostvaruje najveći gubitak zbog umetanja od 10 dB. AWR Microwave Office® koristi se za simulaciju električnog kruga i za određivanje njegovih S-parametara. Za konstruiranje induktora s točnim vrijednostima u 2,45 GHz rabljen je Sonnet® dok je Cadence® rabljen za razmještaj kondenzatora i otpornika.Radio frequency identification (RFID) is one of the most rapidly growing technologies to be utilized in almost every sector for storing and retrieving data wirelessly. Current advancements in CMOS technology help the scientists and technologists to reduce the size and improve the functionalities of the RFID circuits. In this paper, the design of an RF-CMOS power splitter circuit in 0,18 µm Silterra RF-CMOS technology is illustrated for a 2,45 GHz RFID reader. Wilkinson power divider is chosen for the proposed power splitter circuit with on-chip inductors and capacitors. The proposed power splitter achieves a maximum insertion loss of 10 dB. AWR Microwave Office® is used for the simulation of the circuit and for determination of its S-parameters. To design the inductors with accurate values in 2,45 GHz Sonnet® is used whereas Cadence® is used for capacitor and resistor layout

Vibration energy harvesting using single and comb-shaped piezoelectric beam structures: modeling and simulation

Of late, many have shown great interests in the area of energy harvesting or energy scavenging. Researchers have been venturing into methods that can generate acceptable level of voltage since decades ago. In line with the spirit of green technology, energy harvesting will be a major contributor towards saving our environment in near future. Vibration energy harvesting, specifically, is getting more and more attention nowadays. With the abundant sources, this type of energy harvesting can generate desired voltage to power any low power devices and wireless sensor; and subsequently high power devices in the future. In this research, unimorph piezoelectric energy harvester is chosen to harvest wideband mechanical energy. The derivation of the mathematical modelling is based on the Euler-Bernoulli beam theory. MATLAB and COMSOL Multiphysics software are used to study the influence of the structure in generating output voltage due to base excitations. Finally, the results of the frequency response are displayed in the form of voltage within frequency range of 0 to 3500 Hz, at which the comb-shaped piezoelectric beam structure shows better performance as there exist more natural frequencies in the specified range of frequency

The impact of scaling on single event upset in 6T and 12T SRAMs from 130 to 22 nm CMOS technology

As transistor sizes scale down to nanometres dimensions, CMOS circuits become more sensitive to radiation. High-performance static random access memory (SRAM) cells are prone to radiation-induced single event upsets (SEU) which come from the natural space environment. The SEU generates a soft error in the transistor due to the strike of an ionizing particle. Thus, this paper compares the endurance of 12T SRAM and 6T SRAM circuit on 130 up to 22 nm CMOS technology towards SEU. Besides that, this paper discusses the trend of critical linear energy transfer (LET) and collected charge due to technology scaling for the respective circuit. The critical LET (LETcrit) and critical charge (Qcrit) of 6T are approximately 50% lower compared with 12T SRAMs

Content Cytotoxicity Studies of Colorectal Carcinoma Cells Using Printed Impedance Sensors

Monitoring the effectiveness of drugs on cancer cells is crucial for chemotherapeutics studies. In-vitro cell-based biosensors can be used as an alternative for characteristic studies of cells' response to drugs. Cell-based sensors provide real-time measurements and require smaller sample volumes compared to conventional T-flask measurement methods. This paper presents a biosensor that detects in real-time, impedance variations of human colon cancer, HCT-116 cells when treated with anti-cancer agent, 5-Fluorouracil (5-FU). Two different extracellular matrix (ECM); polyaniline and gelatin were tested and evaluated in terms of attachment quality. Polyaniline was found to provide the best attachment for HCT-116 cells and was used for cytotoxicity studies. Cytokinetic behavior indicated that 5-FU inhibited HCT-116 cells at IC50 of 6.8 µg/ mL. Trypan blue exclusion method for testing cell viability was used to validate the impedance measurements, where the cancer cell concentrations were reduced to ~35% when treated with 2.5 µg/mL, and 50% when treated with 6.8 µg/mL. The results generated by the microfabricated impedance biosensor are comparable to the Trypan blue method since both gave similar cell growth trend. It can be concluded that the impedance biosensor has potential to be used as an alternative method in drug testing applications.Monitoring the effectiveness of drugs on cancer cells is crucial for chemotherapeutics studies. Invitrocell-based biosensors can be used as an alternative for characteristic studies of cells' response todrugs. Cell-based sensors provide real-time measurements and require smaller sample volumescompared to conventional T-flask measurement methods. This paper presents a biosensor that detects inreal-time, impedance variations of human colon cancer, HCT-116 cells when treated with anti-canceragent, 5-Fluorouracil (5-FU). Two different extracellular matrix (ECM); polyaniline and gelatin were testedand evaluated in terms of attachment quality. Polyaniline was found to provide the best attachment forHCT-116 cells and was used for cytotoxicity studies. Cytokinetic behavior indicated that 5-FU inhibitedHCT-116 cells at IC50 of 6.8 μg/mL. Trypan blue exclusion method for testing cell viability was used tovalidate the impedance measurements, where the cancer cell concentrations were reduced to ~35% whentreated with 2.5 μg/mL, and 50% when treated with 6.8 μg/mL. The results generated by themicrofabricated impedance biosensor are comparable to the Trypan blue method since both gave similarcell growth trend. It can be concluded that the impedance biosensor has potential to be used as analternative method in drug testing applications