Using the piezoelectric backscatter signal for remote sensing of neural signals

In recent studies, various methods to sense neural signals are used and new methods for remote sensing of neural signals are being developed. However, there are still major difficulties in building long-term implantable neural interface systems that can reliably record neural activity and serve as the basis of brain-machine interfaces (BMI). Therefore, this research is conducted to design a remote neural sensing system that is based on modulation of the backscatter signal from a piezoelectric element by the neural signals. The hypothesis is that if the neural signal is detected with a simple amplifier and the output of this amplifier is connected in parallel to a piezoelectric element, the backscattered signal from the piezoelectric element should be modulated by the neural signal amplitudes. To this end, the echo signal from the piezoelectric element is analyzed and the effect of a load resistor is demonstrated. And then, an electronic circuit to implement the modulation function is simulated on the computer and constructed. The experimental results support the main hypothesis of the project

A Three – tier bio-implantable sensor monitoring and communications platform

One major hindrance to the advent of novel bio-implantable sensor technologies is the need for a reliable power source and data communications platform capable of continuously, remotely, and wirelessly monitoring deeply implantable biomedical devices. This research proposes the feasibility and potential of combining well established, ‘human-friendly' inductive and ultrasonic technologies to produce a proof-of-concept, generic, multi-tier power transfer and data communication platform suitable for low-power, periodically-activated implantable analogue bio-sensors. In the inductive sub-system presented, 5 W of power is transferred across a 10 mm gap between a single pair of 39 mm (primary) and 33 mm (secondary) circular printed spiral coils (PSCs). These are printed using an 8000 dpi resolution photoplotter and fabricated on PCB by wet-etching, to the maximum permissible density. Our ultrasonic sub-system, consisting of a single pair of Pz21 (transmitter) and Pz26 (receiver) piezoelectric PZT ceramic discs driven by low-frequency, radial/planar excitation (-31 mode), without acoustic matching layers, is also reported here for the first time. The discs are characterised by propagation tank test and directly driven by the inductively coupled power to deliver 29 μW to a receiver (implant) employing a low voltage start-up IC positioned 70 mm deep within a homogeneous liquid phantom. No batteries are used. The deep implant is thus intermittently powered every 800 ms to charge a capacitor which enables its microcontroller, operating with a 500 kHz clock, to transmit a single nibble (4 bits) of digitized sensed data over a period of ~18 ms from deep within the phantom, to the outside world. A power transfer efficiency of 83% using our prototype CMOS logic-gate IC driver is reported for the inductively coupled part of the system. Overall prototype system power consumption is 2.3 W with a total power transfer efficiency of 1% achieved across the tiers

Design of Capacitive Micromachined Ultrasonic Transducers for Application in Electronic Travel Aid for the Blind

A low cost, compact Capacitive Micromachined Ultrasonic Transducer (CMUT) based Electronic Travel Aid (ETA) to identify obstacle has been proposed. The aim is to enable free movement of the blind in an environment ridden with stationary obstacles with a target distance of 1-2m. In the present work, SU-8 has been chosen as the membrane material of the CMUT. This has enabled drastic reduction in the DC operating voltage to just 22V- an essential limit for handheld devices to be carried by the user. The CMUT is designed to operate at around 70kHz which minimises frequency dependent loss in air. The simulations are carried out in CoventorWare and COMSOL. The results show that on superimposing an AC of 0.5V on the DC, displacements as large as the gap distance of 5um are obtained resulting in output pressures of 140dB on surface of CMUT. On travelling a to and fro distance of 2m, this pressure drops to about 1uPa. To be able to sense this small pressure, a receiver with thin membrane is designed. A circuit has been implemented off chip to process the received signal and generate a PWM signal to drive the vibrator

Assistive technology interfaces for the blind

Assistive technology devices for the blind are portable electronic devices that are either hand-held or wornby the visually impaired user, to warn of obstacles ahead. Many assistive technology devices use ultrasonic pulse-echo techniques to gauge subject to object distance. Some use infrared light transceivers or laser technology to locate and warn of obstacles. These devices exhibit a number of problems, the most significant of which are related to the interface display that conveys navigation/obstacle warning information to the user. Other sensory channels should not be compromised by the device. This is exactly what can happen when, for example, audio signals are used in obstacle warning on/off displays or more significantly in orientation solutions, where continuous streams of synthetically generated stereo sound mask the natural ambient sound cues used by the blind. Despite the challenges, the commendable feature all these assistive device developers have in common is; they are striving to help a section of the population with a severe disability. Even if there is only partial success in this endevour to assist the blind, the small companies that produce these devices all have the right motive. That is a big step in the right direction. The author has attempted to address some of the problems mentioned in this paper by producing a first working prototype. Improvements to this original design form the basis for ongoing prototype development within the DEBI Institute at Curtin University

Applications on Ultrasonic Wave

This book presents applications on the ultrasonic wave for material characterization and nondestructive evaluations. It could be of interest to the researchers and students who are studying on the fields of ultrasonic waves

Outdoor obstacle detection using ultrasonic sensors for an autonomous vehicle ensuring safe operations

Ultrasonic or sonar sensors are widely used for range finding for indoor and outdoor applications in robotics. However, for outdoors applications, they pose different environmental challenges. Ultrasonic sensor can be used both in air and underwater. It emits acoustic pulses in a cone shaped form in its surroundings and waits for the echoes from the objects nearby that lie within its working range. Ultrasonic sensors have convincing advantages over other sensors. However, sonar sensors have different practical limitations as well which need to be carefully dealt with while working with these sensors. Ultrasonic sensors have several applications in electronics and robotics including obstacle detection and avoidance, mapping and navigation, object recognition and identification. Ultrasonic sensors are widely used in automatic car parking systems in modern vehicles, where two to four sensors are mounted in rear bumper for detecting obstacles up to 2.5 meter and assisting the driver about the parallel parking. The thesis is mainly divided into two parts. In the first part, background studies and literature review is presented which describes sonar sensing principle, applications, advantages, limitations and outdoor sensing challenges. In the second part, a sonar system for obstacle detection for a mobile machine is implemented and its tests and results are discussed. The study indicates the testing of ultrasonic sensors for obstacles detection for an autonomous mobile vehicle outdoor. The sensors were tested both on static frame and on real machine detecting different obstacles from 60 cm up to five meters. The results are better when the object is in front or moving along the axis of the sensor. The sensors are connected in series and are in ranging mode all the time. The experimental results show that the environmental factors like, air turbulence and temperature change affect the speed of sound in air and measuring range. The ranging value is better indoors than the outdoors for same obstacles. However, the results are better on less windy day and also when the surface is strong reflector. It is noted that the results get improved when a cone made of paper or plastic is wrapped around the transducer. The sensor is protected with a water proof casing made of PVC plastic material and it is noted that the casing made of aluminum does not yield good results as compared with the plastic casing. The two or more sensors attached in line increase the covering area of the system

Inferring bread doneness with air-pulse/ultrasonic ranging measurements of the loaf elastic response

This research marks the discovery of a method by which bread doneness may be determined based on the elastic properties of the loaf as it bakes. The purpose of the study was to determine if changes in bread characteristics could be determined by non-contact methods during baking, as the basis for improved control of the baking process. Current control of the baking process is based on temperature and dwell time, which are determined by experience to produce a produce which is approximately done. There is no direct measurement of the property of interest, doneness;An ultrasonic measurement system was developed to measure the response of the loaf to an external stimulus. Doneness, as reflected in the internal elastic consistency of the bakery product, is assessed in less than 1/2 second, and requires no closer approach to the moving bakery product than about 2 inches. The system is designed to be compatible with strapped bread pans in a standard traveling-tray commercial oven