A volumetric display for visual, tactile and audio presentation using acoustic trapping

Science-fiction movies such as Star Wars portray volumetric systems that not only provide visual but also tactile and audible 3D content. Displays, based on swept volume surfaces, holography, optophoretics, plasmonics, or lenticular lenslets, can create 3D visual content without the need for glasses or additional instrumentation. However, they are slow, have limited persistence of vision (POV) capabilities, and, most critically, rely on operating principles that cannot also produce tactile and auditive content. Here, we present for the first time a Multimodal Acoustic Trap Display (MATD): a mid-air volumetric display that can simultaneously deliver visual, auditory, and tactile content, using acoustophoresis as the single operating principle. Our system acoustically traps a particle and illuminates it with red, green, and blue light to control its colour as it quickly scans through our display volume. Using time multiplexing with a secondary trap, amplitude modulation and phase minimization, the MATD delivers simultaneous auditive and tactile content. The system demonstrates particle speeds of up to 8.75m/s and 3.75m/s in the vertical and horizontal directions respectively, offering particle manipulation capabilities superior to other optical or acoustic approaches demonstrated to date. Beyond enabling simultaneous visual, tactile and auditive content, our approach and techniques offer opportunities for non-contact, high-speed manipulation of matter, with applications in computational fabrication and biomedicine

Modeling and Simulation of Acoustic Pressure Field for Ultrasonic Tactile Displays

As the virtual and augmented reality industry continues to grow, it is important to develop a tactile display technology that can seamlessly integrate into a multimodal VR experience. Ultrasonic haptic display technology uses a phased array of ultrasound transducers to create a mid-air pressure focal point, and a modulation of this radiation field at a frequency around 100-300 Hz can stimulate the mechanoreceptors in the skin to produce a tactile sensation. Optimizing this technology to create a strong pressure intensity and focality at low cost and in small space can help open up a new commercial market for tactile displays.This study explores the creation of a simple and modularized pressure field simulator for ultrasonic haptic displays using a simplified model of transducer radiation pattern. The radiation behavior is broken down to a combination of an on-axis radiation behavior and a directivity behavior, each modeled by an exponential and a Gaussian function, respectively. Then, some physical characteristics of phased array are examined to evaluate their influence on peak intensity of focal peak, focal radius, and number of significant secondary focal peaks. The results of the simulator are then compared against the real pressure field of a haptic display prototype

Design of an acoustically transparent pressure sensor for breast elastography

Breast cancer is the most commonly occurring cancer in women. Only in 2018 there were over 2 million new cases all over the world. The MURAB project, pursued at the University of Twente, has the aim to improving the breast biopsy procedure by reducing costs, patient discomfort and false negative rates. A 7-DOF KUKA robot arm steers an ultrasound transducer along a precise scanning trajectory to gather 3D volume image and stiffness values of the breast. Elasticity is the property of a body to be deformed and differs between tumors tissue and soft tissue. Elastography is a non-invasive technique in which the elasticity of a tissue is determined. The aim of this study is to design an acoustically transparent pressure sensor, mounted on the tip of the ultrasound probe, that can measure pressure differences across its surface during the scan, and assess elastographic measurements. The main idea is to use a pad of a characterized material and sequentially ultrasound images able to visualize the section of the pad and evaluate its deformation during time. The transmission of ultrasound waves into a solid depends on the mechanical characteristics of the material and on its physic state. In this work the relations between the acoustic properties and the mechanical behavior of an acoustically transparent pad are studied and evaluated

Tactile Sensing System for Lung Tumour Localization during Minimally Invasive Surgery

Video-assisted thoracoscopie surgery (VATS) is becoming a prevalent method for lung cancer treatment. However, VATS suffers from the inability to accurately relay haptic information to the surgeon, often making tumour localization difficult. This limitation was addressed by the design of a tactile sensing system (TSS) consisting of a probe with a tactile sensor and interfacing visualization software. In this thesis, TSS performance was tested to determine the feasibility of implementing the system in VATS. This was accomplished through a series of ex vivo experiments in which the tactile sensor was calibrated and the visualization software was modified to provide haptic information visually to the user, and TSS performance was compared using human and robot palpation methods, and conventional VATS instruments. It was concluded that the device offers the possibility of providing to the surgeon the haptic information lost during surgery, thereby mitigating one of the current limitations of VATS

Design of Novel Sensors and Instruments for Minimally Invasive Lung Tumour Localization via Palpation

Minimally Invasive Thoracoscopic Surgery (MITS) has become the treatment of choice for lung cancer. However, MITS prevents the surgeons from using manual palpation, thereby often making it challenging to reliably locate the tumours for resection. This thesis presents the design, analysis and validation of novel tactile sensors, a novel miniature force sensor, a robotic instrument, and a wireless hand-held instrument to address this limitation. The low-cost, disposable tactile sensors have been shown to easily detect a 5 mm tumour located 10 mm deep in soft tissue. The force sensor can measure six degrees of freedom forces and torques with temperature compensation using a single optical fiber. The robotic instrument is compatible with the da Vinci surgical robot and allows the use of tactile sensing, force sensing and ultrasound to localize the tumours. The wireless hand-held instrument allows the use of tactile sensing in procedures where a robot is not available

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 12th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2020, held in Leiden, The Netherlands, in September 2020. The 60 papers presented in this volume were carefully reviewed and selected from 111 submissions. The were organized in topical sections on haptic science, haptic technology, and haptic applications. This year's focus is on accessibility