Sub-Nanowatt Ultrasonic Bio-Telemetry Using B-Scan Imaging

Figures

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  Fig. 1.. (a) Principle of M-scan telemetry as reported in [12]; (b) Illustration of a typical M-scan image when the data is being transmitted using ON-OFF signaling. (c) BER corresponding to the M-scan telemetry link as reported in [12] when the transmit power is varied from 1 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\mu$\end{document} W to 12 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\mu$\end{document} W. (d) Principle of the proposed B-scan telemetry. (e) Illustration of a typical B-scan image showing the presence of transmitted data in a 2D cross-section as well as across several B-scan frames. (f) Anticipated improvement in SNR (highlighted by star) for B-scan telemetry compared to M-scan telemetry scheme when operated around beam-angle (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym}…

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  Fig. 2.. (a) Illustration of the experimental setup used to verify and quantify the performance of B-scan telemetry in a water transmission medium. A linear transducer array is driven by (b) an echoscope which is used to acquire B-scan images which are then post-processed on a (c) computer; (d) Picture of the water-bath highlighting the interrogation depth and the relative orientation of the imager and the implant; (e) The prototype of the ultrasound transmitter implemented using a TI CC1310 board and enclosed in a sealed waterproof container. (f) RF module is used for remote programming of the submerged ultrasound.

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  Fig. 3.. Measured \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$S_{11}$\end{document} characteristics of the ultrasound transmitter crystal shown in the inset.

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  Fig. 4.. Illustration of the B-scan image transformation steps using a (a) template imaging stub where the original B-scan image (b) is transformed pixel-wise into Cartesian coordinates (c); (d) Difference image recovered by high-pass filtering the B-scan image frames; (e) Pixel intensity distributions estimated for a given frame at different instances of time. (f) Anticipated change in pixel intensity distributions in the presence and absence of transmission signal.

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  Fig. 5.. (a) Sample B-scan image frame when the transmitter is OFF and the corresponding transformed image (b) after filtering and the (c) column-wise mean intensity vector \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\bar{I}$\end{document}; (d) Sample B-scan image frame when the transmitter is ON and the corresponding transformed image (e) after filtering and the (f) column-wise mean intensity vector \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$\bar{I}$\end{document}; (g)-(i) Pixel intensity distributions corresponding to different image patches (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$R_1$\end{document},…

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  Fig. 6.. (a) High-pass filtered B-scan image frames measured at different magnitudes of transmitted power; (b) Estimated mean and std. deviation for an image patch for different levels of transmitted power; (c) Estimated BER when the transmitted power is varied from 10 - 700 nW. Inset highlights two operating regions (1-20 nW and 100nW) where sensitivity analysis has been performed.

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  Fig. 7.. Sensitivity analysis in the low BER region where the transmitted power \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$P_T = \text{101.5 nW}$\end{document}: (a) Mean and std. deviation values of the image patches; (b) the estimated BER when the magnitude of the transmitted pulsed is varied in increments of 1.2 mV-12 mV. Sensitivity analysis in the low BER region where the transmitted power \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$P_T = \text{0 nW}$\end{document}: (c) Mean and std. deviation values of the image patches; (d) the estimated BER when the magnitude of the transmitted pulsed is varied in increments of 1.2 mV-120 mV.

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  Fig. 8.. Emulation of the ultrasound transmitter driven by an unregulated power source using (a) programmable DAC and a PWM module; (b) Comparison of estimated transmit power levels for the regulated and the unregulated case; (c) Mean, standard deviation and BER measured for levels of transmit power for the unregulated case; (d) Comparison of the BER for the regulated and the unregulated case for different values of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$V_{max}$\end{document}.