Response of a biologically inspired MEMS differential microphone diaphragm

Tan, Lin Lin; Miles, Ronald N.; Weinstein, M.G.; Miller, Raanan A.; Su, Quang T.; Cui, Weili; Gao, Jia

doi:10.1117/12.448378

Cited by 16 publications

(12 citation statements)

References 3 publications

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“…c = o = 1. It is found that the predicted thermal noise fl oor of the conventional microphone is 40.4 dBA while that of the Ormia differential microphone is 20.8 dBA [Tan et al, 2002].…”

Section: Differential Microphone Acoustic Performancementioning

confidence: 95%

“…These quantities may be readily determined by using the detailed fi nite element model. We have shown that this lumped-parameter model, where the parameters are identifi ed by the fi nite element method, yields accurate predictions of the response of the diaphragms to sound [Tan et al, 2002].…”

Section: Differential Microphone Acoustic Performancementioning

confidence: 99%

“…The earliest design consisted of a membrane, or thin plate, supported along its perimeter and stiffened and tuned with masses in order to emphasize the response to the difference in pressure [Gibbons and Miles, 2000;Miles et al, 2001;Yoo et al, 2002]. Lessons learned from the analysis and fabrication of this structure led to the realization that a considerably more compliant (and hence more responsive to sound) diaphragm could be constructed if it was fashioned out of a stiffened plate and supported by carefully designed hinges as shown in fi gure 4 [Miles et al, 2001;Tan et al, 2002]. In this design, rather than attempt to construct a diaphragm that possesses both the rocking and translational modes of Ormia's ear (as shown in fi gure 2 ), we sought the more modest goal of constructing a pressure gradient microphone that responds primarily with the rocking mode; the stiffness of the structure was designed so that the natural frequency of the translational mode of fi gure 2 was above the frequency range of interest (approximately 40 kHz).…”

Section: The Evolution Of the Engineering Designbiomimetic Directionamentioning

confidence: 99%

“…The sensitivities of the differential microphone concepts shown in fi gure 3 may be estimated from: Predicted acoustic responses for the two microphone diaphragm designs show that the Ormia microphone has approximately 20 dB greater sensitivity of the conventional microphone over the audible frequency range [Tan et al, 2002].…”

Section: Differential Microphone Acoustic Performancementioning

confidence: 99%

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The Development of a Biologically-Inspired Directional Microphone for Hearing Aids

Miles

Hoy

2006

Audiol Neurotol

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The development of novel microfabrication techniques for producing a directional microphone for hearing aids is here described. The mechanisms underlying both the structure and function of these unusual microphones were originally inspired by the ears of an inconspicuous insect, the parasitoid fly Ormia ochracea. The structure of Ormia’s ears inspired new approaches to design directional microphones that are more sensitive and have lower thermal noise than that typical of those using traditional approaches. The mechanisms for directional hearing in this animal are discussed along with the engineering design concepts that they have inspired, because they illustrate how basic research can inspire technology development–translational research. However, to realize the potential of bioexploitation this microphone diaphragm concept would have been very difficult to realize without the availability of new silicon microfabrication technologies. Thus, this report can be viewed as an example of what may be possible with the application of new fabrication methods to microphones. Challenges and opportunities provided by the use of silicon microfabrication technology for microphones are discussed.

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“…c = o = 1. It is found that the predicted thermal noise fl oor of the conventional microphone is 40.4 dBA while that of the Ormia differential microphone is 20.8 dBA [Tan et al, 2002].…”

Section: Differential Microphone Acoustic Performancementioning

confidence: 95%

Section: Differential Microphone Acoustic Performancementioning

confidence: 99%

Section: The Evolution Of the Engineering Designbiomimetic Directionamentioning

confidence: 99%

Section: Differential Microphone Acoustic Performancementioning

confidence: 99%

See 2 more Smart Citations

The Development of a Biologically-Inspired Directional Microphone for Hearing Aids

Miles

Hoy

2006

Audiol Neurotol

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“…See-saw models' defining characteristic is a pivot between two unclamped diaphragms. An early iteration of this design from Miles et al [19,28,29] used a polysilicon diaphragm supported with well-distributed crossed stiffeners [30 ,31,32] to tailor the relative sensitivities of the rocking and translational modes of the device while lowering the overall mass. As with most of the designs, amplification of directional cues occurs only in a single narrow working frequency band [33][34][35].…”

mentioning

confidence: 99%

Insect-inspired acoustic micro-sensors

Reid

Windmill

2018

Current Opinion in Insect Science

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Micro-Electro Mechanical System (MEMS) microphones inspired by the remarkable phonotactic capability of Ormia ochracea offer the promise of microscale directional microphones with a greatly reduced need for post-processing of signals. Gravid O. ochracea females can locate their host cricket's 5 kHz mating calls to an accuracy of less than 2 despite having a distance of approximately 500 mm between the ears. MEMS devices base on the principles of operation of O. ochracea's hearing system have been well studied, however commercial implementation has proven challenging due to the system's reliance on carefully tailored ratios of stiffness and damping, which are difficult to realize in standard MEMS fabrication processes, necessitating a trade-off between wideband operation and sensitivity. A survey of the variety of strategies that have been followed to address these inherent challenges is presented. IntroductionThe traditional method of sound source localization is to build a microphone array which combines at least two independent omnidirectional microphones [1]. Calculating the incident angle of sound waves then depends on the separating distance (i.e. time delay) between the microphones receiving the plane waves [2][3][4]. Similar to microphone arrays, many large animals including human beings have two ears with sufficient separation that the nervous system is able to resolve the interaural time difference (ITD) and interaural intensity difference (IID) to determine the source location. The requirement for spatial separation poses a fundamental problem for sound localization in small animals [5] and in micro-scale devices (i.e. Micro-Electro-Mechanic-System (MEMS) devices) smaller than the wavelength of interest.In the 1990's, O. ochracea was found to have a great capability for detecting sound source [6,7 ,8]. The parasitic female Ormia uses auditory cues to localize the mating call of a host Gryllus, a genus of cricket, and then deposits its predaceous larvae on the host [9]. The cricket's mating call has a fundamental frequency around 5 kHz and wavelength at approximately 70 mm, compared to the interaural distance of Ormia that is only around 520 mm [10,11]. Despite the extremely small distance that gives the original maximum ITD and IID as approximately 1.5 ms and 1 dB [12], respectively, experimental investigations show that it can localize the mating call with a resolution less than 2[13]. This high accuracy is attributed to the mechanical coupling structure of Ormia's ear, as shown in Figure 1(a) and (b), which enhances both ITD and IID by up to 40 times greater than the original values at 5 kHz [14 ]. The first resonance is a rocking mode about the bridge centre point, and the second is a translational mode with each end of the bridge moving in-phase while the bridge bends in the middle as shown in Figure 1(c). The response of the Ormia ear at any frequency is then described by a linear combination of these resonance modes [15 ].Ormia-inspired MEMS microphone designs can be broadly separated into two...

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