Chipless wireless neural probes based on one-port surface acoustic wave delay line and neural-firing-dependent capacitors

Jung, In Ki; Fu, Chen; Lee, Kee Keun

doi:10.7567/jjap.53.06jm07

Cited by 3 publications

(3 citation statements)

References 33 publications

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“…The control equation for COM modelling is expressed as [9, 10]

\begin{matrix} right leftthickmathspace.5em \\ \frac{\partial U_{+} (x)}{\partial x} & = - j θ_{normalU} U_{+} (x) - j k U_{-} (x) + j α V \\ \frac{\partial U_{-} (x)}{\partial x} & = - j k^{*} U_{+} (x) - j θ_{normalU} U_{-} (x) - j α V \\ \frac{\partial I (x)}{\partial x} & = 2 j ζ U_{+} (x) + 2 j ζ U_{-} (x) - j ω C_{normals} V \\ θ_{normalU} & = \frac{2 π (f - f_{0})}{v} - normalj γ \end{matrix}

Here, U ± ( x ) is the amplitudes of the SAW in both forward and reverse directions; V is the voltage applied to the terminal of the IDT; I is the current generated by the IDT; k and α are the coefficients of transduction and reflectivity, respectively; C s and γ are the static capacitance and propagation loss per unit length, respectively; f 0 is the operating frequency; and v is the velocity of the SAW.…”

Section: Com Analysis For Saw Sensorsmentioning

confidence: 99%

Analysis and test of a wireless impedance‐loaded SAW sensor

Xing¹,

Xie²,

Wang³

2019

Micro & Nano Letters

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Instead of a conventional wireless transceiver system that requires batteries and complex circuits, the surface acoustic wave (SAW) sensor enables wireless passive measurement. A sensor consisting of an SAW device and external impedance sensing element is analysed. Since the reflection coefficient of the reflective grating on the SAW device depends on the load impedance, the echo characteristics are influenced by the change in the impedance of external sensing element. A resistance sensor or a capacitive sensor is selected as the external sensing element. The two different types of sensors are simulated using coupling-of-mode (COM) modelling, and the relationships between amplitude and phase with load impedance are analysed. On the basis of COM theory, a wireless impedance-loaded SAW sensor is fabricated by the lift-off process and tested by a network analyser to verify the simulation results. It is observed that the test results agree well with the simulation results. The phase change is more sensitive than the amplitude based on the results obtained. The sensitivity is 0.274°/Ω for the sensor with resistance and the sensitivity of the sensor with capacitance is 1.096°/pF. These results can guide the design of the high sensitivity impedance-loaded SAW sensors in the future.

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“…The control equation for COM modelling is expressed as [9, 10]

\begin{matrix} right leftthickmathspace.5em \\ \frac{\partial U_{+} (x)}{\partial x} & = - j θ_{normalU} U_{+} (x) - j k U_{-} (x) + j α V \\ \frac{\partial U_{-} (x)}{\partial x} & = - j k^{*} U_{+} (x) - j θ_{normalU} U_{-} (x) - j α V \\ \frac{\partial I (x)}{\partial x} & = 2 j ζ U_{+} (x) + 2 j ζ U_{-} (x) - j ω C_{normals} V \\ θ_{normalU} & = \frac{2 π (f - f_{0})}{v} - normalj γ \end{matrix}

Section: Com Analysis For Saw Sensorsmentioning

confidence: 99%

Analysis and test of a wireless impedance‐loaded SAW sensor

Xing¹,

Xie²,

Wang³

2019

Micro & Nano Letters

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show abstract

“…The large K 2 allows a large amplitude of AC voltages at output IDTs with a small input voltage. [27][28][29][30] The 400 MHz center frequency was chosen for a reasonable antenna size and for diodes and capacitors to follow the AC signals well. The mixed P-matrix and FFT program were used to obtain the reflection coefficient S 11 in the frequency domain.…”

Section: Com and Spice Modelsmentioning

confidence: 99%

Development of wireless, chipless neural stimulator by using one-port surface acoustic wave delay line and diode–capacitor interface

Kim¹,

Kim²,

Lee³

2017

Jpn. J. Appl. Phys.

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For the first time, a wireless and chipless neuron stimulator was developed by utilizing a surface acoustic wave (SAW) delay line, a diode–capacitor interface, a sharp metal tip, and antennas for the stimulation of neurons in the brain. The SAW delay line supersedes presently existing complex wireless transmission systems composed of a few thousands of transistors, enabling the fabrication of wireless and chipless transceiver systems. The diode–capacitor interface was used to convert AC signals to DC signals and induce stimulus pulses at a sharp metal probe. A 400 MHz RF energy was wirelessly radiated from antennas and then stimulation pulses were observed at a sharp gold probe. A ∼5 m reading distance was obtained using a 1 mW power from a network analyzer. The cycles of electromagnetic (EM) radiation from an antenna were controlled by shielding the antenna with an EM absorber. Stimulation pulses with different amplitudes and durations were successfully observed at the probe. The obtained pulses were ∼0.08 mV in amplitude and 3–10 Hz in frequency. Coupling-of-mode (COM) and SPICE modeling simulations were also used to determine the optimal structural parameters for SAW delay line and the values of passive elements. On the basis of the extracted parameters, the entire system was experimentally implemented and characterized.

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“…2). The propagating SH wave is partially reflected by split-type reflectors, reconverted into EM waves by IDTs, and then the EM energy is transmitted to the network analyzer through the antenna [15][16][17][18][19]. The varicap diode interconnected with sharp metal tips via opamp was electrically linked to split-type reflectors on one-port SAW reflective delay line for neural firing detection.…”

Section: Introductionmentioning

confidence: 99%