Abstract
The present study proposes an assistive device for the bed-ridden persons. The ocular activity of the bed-ridden patients is not lost even during the condition of limited or no motor activities. The proposed device acquires biosignals associated with the eye blinks and activates an alarm or communication protocol. The device is capable of communicating via SMS, e-mail and voice calls to a landline/mobile number once activated. The device can enable the patients to interact with the healthcare-givers whenever they are in need. Hence, the device is supposed to reduce the workload on the healthcare-giver.
TopIntroduction
Incapacitated persons interact with the environment via rehabilitative communication and controlling devices after getting feedback via sensory perceptions. Inability of a person to carry out day-to-day activities, due to dysfunction in any of the interacting organs, concurrently leads to disability. In other words, disability may be defined as a condition where a person loses his ability to interact with the environment by natural means. The most common reasons for disability may be associated with accidents and strokes (Crisostomo, Duncan, Propst, Dawson, & Davis, 1988). Depending on the severity of the disability, there might be loss of speech (partial or total) to severe physical disabilities (e.g. Lou Gehrig's disease, quadriplegia and total body paralysis) (Jackson, Ryndak, & Billingsley, 2000). Across the globe, nearly 100000 patients suffer from Lou Gehrig's disease, also known as amyotrophic lateral sclerosis (ALS) (Vázquez et al., 2008). The mean age for the onset of the disease, across the globe, has been reported as 46-63 years. But the mean age for the onset of the disease in Indian patients is 46 years. Usually, patient suffering from ALS survive 3-5 years from the onset of the disease (Qureshi et al., 2008). Reports suggest that the ALS patients from Indian and African subcontinent survive for longer periods as compared to the patients from rest of the world (Nalini, Thennarasu, Gourie-Devi, Shenoy, & Kulshreshtha, 2008). It is a progressive neurodegenerative disease mainly affecting the motor activities of the adult patients (Miller, Mitchell, Lyon, & Moore, 2007). Since there is a loss of motor activity which affects the muscle strength and coordination, it becomes impossible for the ALS patients to do routine tasks (e.g. climbing steps, getting up from a chair, swallowing or moving their arms, legs and body parts). In many cases, the ALS patients also completely lose their ability to speak. The disease has often been termed as painless paralysis causing atrophy of the muscles. The sensory perceptions (sight, smell, taste, hearing, touch) and the reflex actions of the patients are not affected. This is due to the fact that the functioning of these organs is controlled involuntarily (Miller, Gelinas, & O'Connor, 2004). The oculomotor nuclei are somewhat resistant to the neurodegenerative process. This has been associated with the presence of the glutamate neurotransmitter transporters, responsible for the physiological electrical signal conduction. Due to this reason, there is a residual movement of the eye even at the end-stages of the ALS patients (Dhillon, Singla, Rekhi, & Jha, 2009). Hence, the electrooculogram (EOG) signals can be easily recorded even from the end-stage ALS patients. EOG may be recorded using surface electrodes, placed on either side of an eye. Eye blinks can be easily detected from the EOG patterns. Eye blink signals usually have a potential in the range of 0.4 to 1.0 mV (Heide, Koenig, Trillenberg, Kömpf, & Zee, 1999). The voluntary eye blinks manifest as the highest amplitude potential recorded in the EOG waveform (Venkataramanan, Prabhat, Choudhury, Nemade, & Sahambi, 2005). The magnitude of the biopotential associated with the voluntary blink is highest when the biopotential is recorded in the vertical plane (Müller-Putz, Scherer, Pfurtscheller, & Rupp, 2005). EOG controlled assistive devices have been extensively reported by various groups (Champaty, Pal, & Dash, 2013). The proposed study deals with the designing of a low-cost, semi-automated voluntary blink controlled alerting system using various communication protocols like voice call, SMS and email. An audio-visual alarm was implemented for sending an instant alert to the health caregivers.
Key Terms in this Chapter
Physical Disability: This is an abnormal condition that pertain permanent (total) or partial loss of normal body function or a part of the body related to movement and/or control. The physical disability may be congenital or acquired e.g. spinal-cord injury, cerebral palsy, multiple sclerosis, paraplegia or quadriplegia (acquired spinal injury), amputation, arthritis etc.
Hall-Effect Principle: A current-carrying conductor placed into a magnetic field produces a voltage which is perpendicular to both the current and the field.
Human–Computer Interaction: The branch of technology that interfaces the human with the computer to design a substitute way of controlling or using computer assisted devices or system is known as human-computer interaction (HCI).
Ag/AgCl Electrode: These are surface electrodes widely used for biopotential measurement. Compared to other electrodes, these electrodes have low offset potential, greater stability, better reliability and are low cost and easy to use.
Hall-Effect Sensor: A hall-effect sensor is a transducer whose output voltage varies due to the magnetic field induced by an external magnet placed near to it. It is mostly used in the industries for speed detection and current sensing applications.
NI USB-6008: This is a low-cost multifunctional data acquisition (DAQ) system manufactured by National instruments. The DAQ has a 12-bit resolution with a sampling rate of 10 kS/s. It provides 8 analog inputs (AI) channels, 2 analog output (AO) channels, 12 digital input-output (DIO) channels, a 32-bit counter with a high-speed USB interface. The DAQ is compatible with MATLAB, LabVIEW, Measurement Studio for Visual Studio .NET.
Assistive Devices: These are instruments, products, tools or type of equipment designed, adapted, integrated or interfaced to aid people with physical or mental disability or disorder to accomplish major life activities.
Locomotor Disability: This is a type of physical disability related to movement of total body or a part of it. People with locomotor disability have restriction in moving themselves without any external support (personal or mobility aids) and have lack of abilities to lift/move/pick up things placed near a range considered normal for healthy people.
AT Commands: AT, an abbreviation for ATtention, is the set of commands used to control MODEMs. Every AT command line begins with “AT” or “at” to signify the attention from the MODEM. The starting “AT” in the command line is not the actual command name rather a prefix to a command which tells the MODEM about the beginning of a command line. For example, consider an AT command “ATD”. Here ‘D’ is the actual AT command whereas AT is the prefix to it to inform the MODEM to dial a voice call. Sending only “AT” to the MODEM returns OK which signifies that the communication has been established between the device (used to send the AT command) and the MODEM. The list of AT commands used to test the MODEM and implemented in our program has been tabulated in Table 3 (See Appendix).
Assistive Technologies: These are scientific applications that make use of assistive, rehabilitative and/or adaptive assistive devices for the people with mental or physical impairment like walking, hearing, speaking, typing, writing, remembering, pointing, learning, seeing etc. to enhance, preserve, or improve their functional capabilities. Assistive technologies include prosthesis, hearing aids, mobility aids, visual aids, special computer hardware or software to enhance mobility, vision, hearing, communication and control through interfacing.
Electrooculogram: The corneo-retinal potential developed due to the movement or the rotation of the eye is called as electrooculogram. The eye is considered to be a moving electric dipole.
Electrooculography: The technique involved in the measurement of the corneo-retinal potential is termed as electrooculography.
Instrumentation Amplifier (IA): The IA is a type of differential amplifier with additional input buffer stage to remove the need for input impedance matching. Characteristics like very low DC offset voltage, High CMRR (common-mode-rejection-ratio), high open-loop gain, high input impedance, low noise and low drift make this amplifier widely used in industrial and measurement applications. We have used AD-620 IA which has a differential input and a differential/single ended output (with respect to a reference). It amplifies the voltage difference between two input signals while rejecting the signals common to both the inputs. AD-620 is mostly used in data acquisition, medical application, industries to maintain greater accuracy and stability.
Biosignal: This is also called as bioelectric signal and is originated due to the physiological processes in the living beings. The biosignal can be measured and monitored continuously. Elctroeencephalogram (EEG), electrocardiogram (ECG), electromyogram (EMG), electrooculogram (EOG) etc. are some examples of biosignals originated due to the physiological activities in the human body.
Arduino: This is an inexpensive open-source hardware-software electronic prototyping platform to design or develop interactive, stand-alone and customized objects for monitoring, automation and control. The hardware uses different 8-bit Ateml AVR microcontrollers or 32- bit Atmel ARM processors. The hardware offers flexibility due to accessibility of analog and digital I/O pins, SPI and serial interface, and PWM outputs to interface with various expansion boards (Arduino-compatible shields) and computing systems directly (API programming mode). The Arduino can be programmed through a integrated development environment (IDE) that supports C, C++ and Java. Some examples of Arduino boards are: Arduino UNO, Arduino Diecimila, Arduino Duemilanove Arduino Pro, Arduino Pro Mini, Arduino Micro, Arduino Nano, Arduino Mega, Arduino DUE, Arduino Gemma, Arduino LilyPad, Arduino Leonardo etc.
Contact Bounce: Generally the switches are made up of spring materials. When any switch actuates, the contact touches one another. Under the force of actuation, continuity is expected with single steady moment. But the momentum produced due to mass of the moving contact and the inherent elasticity in this mechanism makes the contact bounce one or several times before achieving a steady contact and coming to a full rest. The contact bounces for a period of milliseconds producing rapid electrical pulses. This effect rarely affects any power circuits, but creates noticeable undesired effect if used in analog or digital logic circuits. Digital circuits misinterpret the electrical ripples produced due to contact bounce as data streams which create undesirable results.