Methods and systems for CMUT resonance determination
A method of determining a resonance frequency of a capacitive micromachined ultrasound transducer may include directing a broadband excitation waveform at an ultrasound transducer, wherein the excitation waveform comprises a frequency band which includes an anticipated resonance frequency of the ultrasound transducer; and measuring a ringdown characteristic of the ultrasound transducer.
1 . A method of characterizing an ultrasound transducer, comprising:
directing a broadband electrical stimulus waveform at an ultrasound transducer, wherein a spectral bandwidth of the broadband electrical stimulus waveform includes an anticipated resonance frequency range of the ultrasound transducer;
measuring a ringdown characteristic of the ultrasound transducer from at least one emitted signal of the ultrasound transducer as a result of the broadband electrical stimulus waveform; and
determining a resonance frequency of the ultrasound transducer based at least in part on the ringdown characteristic.
2 . The method of claim 1 , wherein the ultrasound transducer is coupled to a speculum of an otoscope.
3 . The method of claim 1 , wherein the ultrasound transducer is coupled to a stethoscope for auscultation of internal organs or blood vessels.
4 . The method of claim 1 , wherein the ringdown characteristic of the ultrasound transducer is measured by a Doppler receiver configured to amplify the at least one emitted signal of the ultrasound transducer in response to the broadband electrical stimulus waveform.
5 . The method of claim 4 , further comprising digitizing the at least one emitted signal of the ultrasound transducer.
6 . The method of claim 1 , wherein measuring the ringdown characteristic of the ultrasound transducer comprises calculating a Fourier transform of the at least one emitted signal from the ultrasound transducer in response to the broadband electrical stimulus waveform.
7 . The method of claim 1 , wherein the ringdown characteristic comprises a resonance frequency.
8 . The method of claim 6 , further comprising determining a peak frequency, wherein the peak frequency corresponds to a frequency of a maximum amplitude of the Fourier transform of the at least one emitted signal.
9 . The method of claim 6 , further comprising determining a peak frequency of a plurality of data points of the Fourier transform, wherein determining a peak frequency comprises:
(a) receiving the plurality of Fourier transform data points of the at least one emitted signal of the ultrasound transducer;
(b) determining a polynomial fit of a plurality of data points surrounding the peak frequency of the plurality of Fourier transform data points; and
(c) determining the peak frequency from a maximum of the polynomial fit of the plurality of data points surrounding the peak frequency.
10 . The method of claim 1 , wherein the broadband electrical stimulus waveform comprises a pulsed signal.
11 . The method of claim 10 , wherein the pulsed signal comprises a delta function.
12 . The method of claim 10 , wherein the pulsed signal comprises one or more oscillations, and wherein the pulsed signal comprises at least 1 cycle of oscillation.
13 . The method of claim 12 , wherein the pulsed signal comprises a cycle duration, wherein the cycle duration of the pulsed signal is configured to cover an anticipated range of resonance frequencies of the ringdown characteristic.
14 . The method of claim 10 , wherein the pulsed signal comprises at least one pulse.
15 . The method of claim 1 , wherein the ringdown characteristic is measured after the broadband electrical stimulus waveform is directed at the ultrasound transducer.
16 . The method of claim 1 , wherein at least two broadband electric stimulus waveforms are directed to the ultrasound transducer, and wherein at least two emitted signals of the ultrasound transducer are averaged.
17 . The method of claim 1 , wherein the ringdown characteristic comprises a resonance frequency, wherein the resonance frequency is from 1500 kilohertz (kHz) to about 2000 kHz.
18 . The method of claim 1 , further comprising characterizing the ultrasound transducer as functional or non-functional based on the ringdown characteristic.
19 . The method of claim 18 , wherein the non-functional characterization of the ultrasound transducer comprises a ringdown characteristic outside a predetermined range for the ringdown characteristic of the functional ultrasound transducer.
20 . A computer system for characterizing an ultrasound transducer, comprising:
(a) an ultrasound transducer;
(b) a processor in electrical communication with the ultrasound transducer; and
(c) a non-transient computer readable storage medium including software, wherein the software comprises executable instructions that, as a result of execution cause the processor of the computer system to:
(i) provide a broadband electrical stimulus waveform to the ultrasound transducer, wherein a spectral bandwidth of the broadband electrical stimulus waveform comprises an anticipated resonance frequency range of the ultrasound transducer;
(ii) measure an emitted signal from the ultrasound transducer in response to the broadband electrical stimulus waveform;
(iii) determine a ringdown characteristic of the emitted signal; and
(iv) determine a resonance frequency of the ultrasound transducer based at least in part on the ringdown characteristic.
21 . The method of claim 1 , wherein directing the broadband electrical stimulus waveform at the ultrasound transducer comprises driving the ultrasound transducer with the broadband electrical stimulus waveform.
22 . The method of claim 1 , wherein directing the broadband electrical stimulus waveform at the ultrasound transducer comprises pinging the ultrasound transducer.