Highlights
- We demonstrated for the first time the use of TENG for patient rehabilitation.
- The Rehab-TENG could be used as game controller to test patients’ motor function.
- Energy harvested by the Rehab-TENG was a motivating factor for patient to exercise.
- Capacitor charging behavior was correlated to patients’ impairment level.
- Survey questionnaire showed high motivatability and practicability of Rehab-TENG.
Abstract
Recent rehabilitation methods for physical impairments utilize various technologies such as robotic devices and gaming software in order to assist, motivate, and facilitate the recovery process. While most of the rehabilitation devices require external power sources, the triboelectric nanogenerator (TENG) has been proven as a reliable self-powered sensor that can also be used as an energy harvester. In this work, we utilize the TENG as a game controller as well as an exercise device for patients undergoing rehabilitation. We show that since the TENG can store energy, it serves as a motivating factor for the patient, as well as an index to monitor progression of rehabilitation and any improvements they make during rehabilitation. First, we describe the working principle of the TENG-based rehabilitation device (Rehab-TENG) and perform parametric studies to determine the performance of the device. Second, we developed a circuit to digitize the TENG output so that the patient could use the Rehab-TENG to control a computer game via Bluetooth. Third, the Rehab-TENG was employed as an energy harvester in an exercise system, where the patient moved their impaired arm to store energy into a capacitor. Based on the speed of capacitor charging, the level of impairment could be estimated. Finally, the patients were asked to answer a questionnaire where they emphasized the practicability of the device for its use as a home-based rehabilitation system and the harvesting of energy as a motivating factor for them to move their impaired body part more than they normally would. We expect this study will enhance the potential of TENG use in healthcare as a practical tool for patient rehabilitation.
1. Introduction
Rehabilitation is the process of helping a patient recover their mental and physical abilities that they have lost due to injuries. Physical rehabilitation is essential after the neurological injuries such as stroke, cerebral palsy, and spinal cord injuries. Such injuries lead to motor impairment caused due to damage to the central and/or the peripheral nervous system that prevents voluntary limb motion. Several specialized devices with varying degrees of complexity have been developed and used for patient rehabilitation depending on the type of impairment and injuries. The rehabilitation techniques aim to evoke neuroplasticity to regain the motor functions [1]. Rehabilitation methods dealing with motor disabilities and recovery of physical abilities often utilize gaming as a means to motivate the patient. While rehabilitation is usually a difficult and boring process for the patient, the use of computer gaming can make the experience fun, and the difficulty level of the computer game can be adjusted for optimal results depending on the patient impairment level expediting the patient recovery [2], [3]. Since computer gaming usually requires coordination between the sensory inputs, the brain, and the limbs, it is one attractive method to help the patients recover their lost motor abilities as well as help with other physical impairments. Computer gaming also requires repetition of certain tasks and can thus be used as a form of exercise for the patients.
Healthcare solutions using energy harvesters have been proposed based on solar, electromagnetic, piezoelectric, thermoelectric and triboelectric technologies [4], [5], [6]. Among these the triboelectric nanogenerator (TENG) has been proven to work both as a reliable self-powered sensor and energy harvester. It has been shown to sense human body motion such as joint angle or movement speed [6], [7], [8]. Such TENGs can be also used as a robot controller or an object controller in virtual space after digitizing its output [9], [10], [11], [12], [13]. In order to harvest low frequency human body motion several techniques such as use of gear-train, mainsprings and multi-segmented TENGs have been employed [14], [15], [16]. Wearable TENGs used for harvesting energy from the human body can be designed in various forms depending on the application such as rotational type systems for harvesting joint motion [16], spring-based systems for harvesting body vibrations [17], or body conformable textile-based TENGs [6]. Thus TENGs can be used as sensors, the output of which when digitized can be used in control applications, and wearable TENGs can be used as energy harvesters. The energy harvested from the TENG can then be used to make the system self-powered or at the very least prolong the running time of the battery that is powering the electrical load. The use of TENGs in rehabilitation applications has been previously suggested [18], [19], [20], and especially the possibility of TENGs as sources for electrical neural stimulation has been recently studied [21], [22], [23]. However, there has as yet been no report studying the practical use of TENGs with patients having neurological or physical disabilities. Thus there is a need to explore the issues and benefits of using wearable TENGs as self-powered sensors or energy harvesters in the field of patient rehabilitation, by actually testing them on patients with significant physical impairments and undergoing rehabilitation.
In this work, we develop a non-invasive, wearable and portable TENG for the purpose of patient rehabilitation (Rehab-TENG). The developed Rehab-TENG device can operate as a self-powered sensor to operate as a game controller and communicate via Bluetooth with the game, as shown in Fig. 1a. This application was used to test the motor function skills of the patient. The Rehab-TENG device can also be used as an energy harvester where the patient can use it to charge a capacitor in an exercise system. As shown in Fig. 1b, we found that the lesser the patient impairment and greater their arm strength, the greater the energy harvested. Finally, we conducted a questionnaire survey to assess the efficacy of our Rehab-TENG device. As shown in Fig. 1c, we found that the lesser the patient impairment, the higher the scores given by the patients for motivatability and practicability of the Rehab-TENG. This implies that the patients were encouraged by the energy harvesting aspect of the Rehab-TENG and its practicability for using it in a home setting.
The following is the Supplementary material related to this article Supplementary Movie S2, Supplementary Movie S3 and Supplementary Movie S4.
TBI Rehabilitation 