Wideband double-mode bulk acoustic wave resonator filters on lithium niobate using periodically slotted electrodes

Abstract: This paper discusses applicability of periodically slotted electrodes for realization of wideband transversely-coupled double-mode resonator filters using lithium niobate (LN) thin plate. First, two-dimensional analysis is carried out, and it is shown that the periodic structure is effective to control the frequency separation between two resonance modes, and synthesis of the fractional bandwidth larger than 24% is achievable. Next, 3D analysis is performed for suppression of spurious resonances. It is shown that the mass loading at aperture edges is effective for the piston mode operation, and transverse modes can be well suppressed. It is also pointed out that the bottom electrode should be covered only the aperture region and removed from the busbar and gap regions for suppression of unwanted resonances. With these proper edge treatments, spurious-free and wide passband can be synthesized.

In-Line Detection with Microfluidic Bulk Acoustic Wave Resonator Gas Sensor for Gas Chromatography

A microfluidic film bulk acoustic wave resonator gas sensor (mFBAR) adapted specifically as an in-line detector in gas chromatography was described. This miniaturized vapor sensor was a non-destructive detector with very low dead volume (0.02 μL). It was prepared by enclosing the resonator in a microfluidic channel on a chip with dimensions of only 15 mm × 15 mm × 1 mm. The device with polymer coating showed satisfactory performance in the detection of organophosphorus compound, demonstrating a very low detection limit (a dozen parts per billion) with relatively short response time (about fifteen seconds) toward the simulant of chemical warfare agent, dimethyl methylphosphonate. The in-line detection of the mFBAR sensor with FID was constructed and employed to directly measure the concentration profile on the solid surface by the mFBAR with the controlled concentration profile in the mobile phase at the same time. The difference of peak-maximum position between mobile phase and solid phase could be a convenient indicator to measure mass transfer rate. With the response of the mFBAR and FID obtained in one injection, an injection mass-independent parameter can be calculated and used to identify the analyte of interest.

Dual functionality metamaterial enables ultra-compact, highly sensitive uncooled infrared sensor

Cointegration and coupling a perfect metamaterial absorber (PMA) together with a film bulk acoustic wave resonator (FBAR) in a monolithic fashion is introduced for the purpose of producing ultracompact uncooled infrared sensors of high sensitivity. An optimized ultrathin multilayer stack was implemented to realize the proposed device. It is experimentally demonstrated that the resonance frequency of the FBAR can be used efficiently as a sensor output as it downshifts linearly with the intensity of the incident infrared irradiation. The resulting sensor also achieves a high absorption of 88% for an infrared spectrum centered at a wavelength of 8.2 μm. The structure is compact and can be easily integrated on a CMOS-compatible chip since both the FBAR and PMA utilize and share the same stack of metal and dielectric layers.