Date: August 7, 2017
Adrian David Cheok, Kasun Karunanayaka, Surina Hariri, Hanis Camelia, and Sharon Kalu Ufere Imagineering Institute, Iskandar Puteri, Malaysia & City, University of London,UK.
Phone: +607 509 6568
Fax: +607 509 6713
Here we are excited to introduce the world’s ﬁrst computer controlled digital device developed to stimulate olfactory receptor neurons with the aim of producing smell sensations purely using electrical pulses. Using this device, now we can easily stimulate the various areas of nasal cavity with different kinds of electric pulses. During the initial user experiments, some participants experienced smell sensations including ﬂoral, fruity, chemical, and woody. In addition, we have observed a dif- ference in the ability of smelling odorants before and after the electrical stimulation. These results suggest that this technology could be enhanced to artiﬁcially create and modify smell sensations. By conducting more experiments with human subjects, we are expecting to uncover the patterns of electrical stimulations, that can effectively generate, modify, and recall smell sensations. This invention can lead to internet and virtual reality digital smell.
To date, almost all smell regeneration methods used in both academia and industry are based on chemicals. These methods have several limitations such as being expensive for long term use, complex, need of routine maintenance, require reﬁlling, less controllability, and non-uniform distribution in the air. More importantly, these chemical based smells cannot be transmitted over the digital networks and regenerate remotely, as we do for the visual and auditory data. Therefore, discovering a method to produce smell sensations without us- ing chemical odorants is a necessity for digitizing the sense of smell. Our concept is illustrated in the Figure 1, which is electrically stimulating the olfactory receptor neurons (ORN) and study whether this approach can produce or modify smell sensations. During a medical experiment in 1973, electrical stimulation of olfactory receptors reported some smell sensations including almond, bitter almond, and vanilla . However, three other similar experiments that used electrical stimulation failed to reproduce any smell sensations [2, 3, 4]. Therefore, ﬁnding a proper method to electrically reproduce smell sensations was still undiscovered.
Our approach is different from the previous research mentioned above. Our main objective is to develop a controllable and repeatable digital technology, a device that connects to computers and be easily able to programmed and controlled. Also this device needs to generate electric pulses of different frequencies, cur- rents, pulse widths and stimulation times. To provide more stimulation possibilities, we wanted this device to be capable of stimulating diverse sites at the ventral surface of the inferior, middle, and superior nasal concha. Fig. 2 shows the computer controlled digital device we have developed to stimulate olfactory receptors. The amount of current output by the circuit can be controlled using one of the ﬁve push buttons shown in Figure 2 and the respective LED near the push button will lights up after the selection. The frequency of the stimulation pulses and stimulation time is controlled by the microcontroller program. It is possible to vary the stimulation frequency from 0Hz to 33kHz and pulse width using the programming. The pair of silver electrodes combined with the endoscopic camera was used to stimulate olfactory receptor neurons, and during the stimulation, one electrode is conﬁgured as the positive and the other electrode as the ground. Fig 3 and Fig 4 shows testing our device with human subjects.
During our ﬁrst user study, we have stimulated the 30 subjects using 1mA to 5mA range with frequencies 2Hz, 10Hz, 70Hz, and 180Hz. 1mA at 10Hz and 1mA at 70Hz were the stimulation parameters which gave most prominent results for the smell related responses. Electrical stimulation with 1mA and 70Hz induced the highest odor perceptions. 27% of the participants reported the perceived fragrant and chemical sensa- tions. Other smell sensations that are reported for include, 20% fruity, 20% sweet, 17% tosted and nutty, 10% minty, and 13% woody. Stimulation parameters 1mA/10Hz reported 17% fragrant, 27% sweet 27%, chemical 10%, woody 10%. Meanwhile, results for the 4mA/70Hz reported 82% for pain and 64% reported pressure sensations. We have also probed the effect of electrical stimulation on the nose after stimulation. Therefore, we asked participants to repeat the snifﬁng of known odorants immediately after stimulation and rate the intensity. Most of the participants reported higher intensity after stimulation. This showed that the electrical stimulation increased the intensity of the odorants in the nose.
We are planning to extend this user experiment with more number of participants. The effects of the differ- ent electrical stimulation parameters such as frequency, current, and stimulation period will be more closely studied in future. By analyzing the results, we plan to identify various stimulation patterns that can produce different smell sensations. If the electrical stimulation of olfactory receptors effectively produce smell sen- sations, it will revolutionize the ﬁeld of communication. Multisensory communication is currently limited to text, audio and video contents. Digitizing touch sense are already been achieved experimentally in the research level and will be embedded to daily communication near future. If the digitization of smell be- comes possible it will paved the way for sensing, communicating and reproducing ﬂavor sensations over the internet. This will create more applications in the ﬁelds such as human computer interaction, virtual reality, telepresence, and internet shopping.
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