Analysis of Tongue Pressure Sensor for Biomedical Applications E. Sardini, M. Serpelloni Dep. of Information Engineering, University of Brescia, Brescia, Italy mauro.serpelloni@unibs.it S. Pandini Dep. of Mechanical Engineering, University of Brescia, Brescia, Italy stefano.pandini@unibs.it Abstract— The tongue is an important muscle and the contact with the hard palate during the articulation of a syllable or during swallowing is fundamental. Patients who have had cerebrovascular or other neurological disorders may have impaired speech and swallowing problems due to decreased ability to control the tongue. In this work, a device with the aim of providing a non-invasive aid for the rehabilitation is described. The proposed device has been designed with the purpose of measuring the tongue pressure on the palate directly in the oral cavity and transmitting the data wirelessly. The device is minimally invasive, because no cable is used to connect the pressure sensor placed in the oral cavity with the reading unit placed outside. A first prototype was developed and preliminary testing data for the analysis of the sensor behavior have been performed. A specific experimental setup has been designed and realized and a testing protocol has been defined and adopted. The obtained preliminary experimental results show a wide measurement range, up to 100 kPa. Application fields of this device are the treatment of people with swallowing or phonetic disorders. Keywords— Intraoral sensor, implanted sensor, wireless sensor, physiological monitoring, pressure sensor, thick-film sensor. I. INTRODUCTION The number of patients who had cerebrovascular or other neurological disorders (e.g. Parkinson's disease) is continuously increasing. Usually these patients have trouble swallowing and articulating a sound and they require rehabilitative care [1-2]. The possibility of measuring the tongue pressure against the hard palate during syllable articulation or swallowing is important and, in fact, the contact between tongue and palate is of vital importance for both functions. The techniques usually used are videofluorography (VF) or videoendoscopy (VE). In [3-5], the authors analyzed qualitatively the tongue coordination and jaw movements in chewing and swallowing via VF and VE. However, the application VF widely and repeatedly is not recommended because of the dangers of radiation exposure for patients. Therefore, in the literature, studies on the measurement of tongue contact against the hard palate in a non-invasive manner have been studied recently. In [6-11], different types of pressure sensors are used to measure the tongue pressure. These techniques are based on a sensor in contact with the palate and connected via cables to a conditioning electronics positioned outside the oral cavity. For example in [9], the authors report a pressure sensor for measuring the tongue pressure on the palate using a palatal plate with seven pressure sensors. However, the presence of wired connections, between the oral cavity and the reading unit placed outside, may impair sound articulation or swallowing. Furthermore, the presence of cables can be perceived by the patient as invasive. This problem is widely reported in the literature and different approaches are proposed [12-15]. To overcome this problem, several authors propose devices transmitting information wirelessly between the inside and the outside of the oral cavity. In [13], the authors describe the architecture and the operating principle of a new wireless system for balance control for the falling prevention. The device measures if and where the tongue is in contact with the palate, but does not incorporate a pressure sensor. In [14], the aim was to develop a wireless telemetry method to complement the shortcomings of existing methods that measure the intra-oral pH. In [15], it is reported a prototype system for wireless control of different interfaces. The wireless intraoral device is activated by the tongue, the signals are sent to tens of meters to a coordinator wireless transmitting commands from the intra-oral device to the computer. The sensor operates as a switch by sending the contact information. In this research, we propose a wireless intra-oral device for measuring the tongue pressure on the palate. The presented system is designed to measure the tongue pressure on the palate and wirelessly transmit data to a reading unit placed outside the oral cavity. The device consists of seven sensors connected to an electronic circuit for conditioning and data transmission. The sensors are fabricated using screen printing technique on a plastic substrate at a low temperature. Screen printing technique consists in the deposition of a film of a few microns in thickness in a single step using a mask. This technique allows the manufacture of low cost, light, flexible and biocompatible sensors. The target applications may be different: first of all, these sensors can be used in wearable systems [16] or in implantable systems within the human body, in passive devices or connected to power harvesters [17]. In a previous publication [18], a first device was presented and preliminary experimental results reported up to 80 kPa. We now present an improved version of the device. A new conditioning circuit is introduced and the building blocks are briefly described. Furthermore, the sensor is tested with a new experimental apparatus and according to proper testing protocols, designed so to highlight the correlation between the exerted stress and electrical output. Accurate analyses for a 978-1-4799-2921-4/14/$31.00 ©2014 IEEE