Haptic Device for Hand Rehabilitation for Stroke Patients
Stroke is a major global health problem. With its rapidly aging population, the burden of stroke in Asia is becoming increasingly pronounced. In China, stroke is the leading cause of disability, with approximately 2 million people suffering from stroke each year and 75% of the disabled community expressing need for better rehabilitation devices. In Singapore alone, there will be 6,200, social and rehabilitative day-care places by 2020.
During a stroke, blood supply to the brain is interrupted, due to a blockage or bursting of an artery leading to the brain. When this happens, part of the brain is damaged and as a result, the patient loses control over certain bodily functions. Frequently, this includes loss of motor control in the limbs. Rehabilitation exercises are critical to help stroke survivors regain this motor control, and improve quality of life. Unfortunately, regaining hand function is often a slow process, as the patient needs to do numerous repetitive exercises, to re-wire the brain and recover fine motor skills.
Effective equipment for rehabilitation therapy is crucial in the recovery process. However, currently-available rehabilitation devices for the hand have several disadvantages. They cannot be used to perform hand and forearm exercises simultaneously and have bulky complicated designs, making them difficult for stroke patients to operate. Furthermore, traditional pneumatic handles require changing the handle diameter or moving the arm, which interferes with the training process.
A NUS research team has developed a new hand rehabilitation device to help stroke patients regain hand motor skills, called the Haptic Knob 2 (HK2). This provides a two-degrees-of-freedom interface to help stroke patients recover the ability to open/close their hand as well as rotate their forearm. The HK2 comprises a rotation unit to train the movement of the forearm and a unit to train hand opening/closing based on a CAM mechanism with two rotation centres. This CAM mechanism enables the thumb and fingers to follow movement paths that simulate natural actions of a healthy hand. These two units can be used individually or simultaneously for effective hand rehabilitative therapy. The device handle is integrated with four force sensors to measure the interaction forces and torques with the user’s hand. An ergonomic arm support is also included.
The HK2 device uses haptic technology, which provides tactile feedback through forces, vibrations or motions to the user. This enables the device to induce long-lasting improvements in hand and forearm motor control. Unlike the traditional pneumatic handles, which require changing of handle diameter, continuous, uninterrupted training can be achieved with the HK2. In contrast to other hand rehabilitation devices, the HK2 can be used to perform hand opening/closing exercises as well as forearm rotation exercises simultaneously or individually. Its design is small and simple, and it can be used at both home or in-clinic settings.