Focused ultrasound as a tool to input sensory information to humans (Review)

Abstract

This review is devoted to the analysis of studies and implementations related to the use of focused ultrasound for functional effects on neuroreceptor structures. Special attention was paid to the stimulation of neuroreceptor structures in order to input sensory information to humans. This branch of medical and phys iological acoustics appeared in Russia in the early 1970s and was being efficiently developed up to the late 1980s. Then, due to lack of financial support, only individual researchers remained at this field and, as a result, we have no full fledged theoretical research and practical implementations in this area yet. Many promising possibilities of using functional effects of focused ultrasound in medicine and physiology have remained unimplemented for a long time. However, new interesting ideas and approaches have appeared in recent years. Very recently, very questionable projects have been reported related to the use of ultrasound for targeted functional effects on the human brain performed in some laboratories. In this review, the stages of the development of scientific research devoted to the functional effects of focused ultrasound are described. By activating the neuroreceptor structures of the skin by means pulses of focused ultrasound, one can cause all the sensations perceived by human beings through the skin in everyday life, such as tactile sensations, ther mal (heat and cold), tickling, itching, and various types of pain. Stimulation of the ear labyrinth of humans with normal hearing using amplitude modulated ultrasound causes auditory sensations corresponding to an audio modulating signal (pure tones, music, speech, etc.). Activation of neuroreceptor structures by means of focused ultrasound is used for the diagnosis of various neurological and skin diseases, as well as hearing dis orders. It has been shown that the activation is related to the mechanical action of ultrasound, for example, by the radiation force, as well as to the direct action of ultrasonic vibrations on nerve fibers. The action of the radiation force is promising for the realization of the possibility of blind and even deaf and blind people to perceive text information on a display using tactile sensations caused by ultrasound. Very different methods of using ultrasound for local stimulation of neuroreceptor structures are discussed in this review. Among them are practical methods that have been already tested in a clinic, as well as pretending to be sensational methods that are hardly feasible in the foreseeable future.

Rendering volumetric haptic shapes in mid-air using ultrasound

“…The use of focused ultrasound as a non-invasive method to stimulate neuroreceptor structures in various parts of the human body has been a topic of research since the early 1970s [Gavrilov and Tsirulnikov 2012]. Dalecki et al [1995] first proposed the idea of using water-based ultrasound to create tactile sensations on a finger attached to an acoustic reflector floating at the surface of a water bath.…”

SkinHaptics: Ultrasound focused in the hand creates tactile sensations

“…One of the most intriguing methods for creating tactile sensations in the hand involves focused ultrasound [10], [14]. Gavrilov et al investigated this method as a noninvasive tool for diagnosing diseases that affect the nervous system (e.g., the hearing or the skin).…”

“…Gavrilov et al found that the displacement amplitude was approximately 0.1 micrometer for all threshold intensities and independent of the frequency. However, biological effects (e.g., heating) and the direct action of ultrasound vibrations on nerve fibres could be relevant as well [10].…”

“…Moreover, in medical science focused ultrasound has been used as a noninvasive method for diagnosing hearing and neurological disorders, and for creating tactile, temperature and pain sensations in the hand [10]. As a first step to investigate how ultrasound focused in the hand could provide tactile feedback for human-computer interaction, we present a technology that provides the basis for the device we envision and explore the fundamental requirements for creating tactile sensations.…”

UltraHaptics

“…The displacement caused by the shear wave triggers mechanoreceptors within the skin generating a haptic sensation [11]. The second method bypasses the receptors entirely and directly stimulates the nerve fibres [12]. However, this method requires powerful acoustic fields that penetrate the skin, making it unsuitable for applications designed for prolonged use.…”