**2. Leap motion controller**

Leap Motion Controller (LMC) is a small, portable device that accurately detects all the hand and finger joints [1]. It is a compact device, 8 cm wide by 3 cm high. The top of the device is made of smoked glass to hide the two image sensors and infrared LEDs that work together to track the user's hand movements (**Figure 1**).

It is possible to use the LMC connected directly to the computer in nonimmersive experiences (**Figure 2a**). In this case, the video monitor is used as a viewing device. In immersive experiences, the LMC is coupled to VR glasses, such as a Gear VR. (**Figure 2b**). The simplicity of the LMC could facilitate the approach to

*The Use of Leap Motion in Manual Dexterity Testing by the Box and Blocks Test: A Review Study DOI: http://dx.doi.org/10.5772/intechopen.108191*

#### **Figure 1.**

*Leap motion controller (LMC). Source: Leap motion, 2019 https://www.leapmotion.com/.*

#### **Figure 2.**

*(a) LMC with non-immersive interaction (desktop). (b) LMC with immersive interaction (VR headset). Source: Leap Motion, 2019 https://www.leapmotion.com/.*

technology, increasing the feeling of immersion, imagination, and interaction with the virtual environment [4].

The LMC works with accuracy down to 1/100 mm without visible latency in its visual field. The viewing range is 80 cm above and around the device. This limit occurs due to the propagation of the LED light through space since it is difficult to infer the hand's position from a certain distance.

The LMC is postulated as a playful tool that can favor the inclusion of participants in a different environment, in which they can face new challenges and achieve new goals by interacting in real time with hand and finger movements, functioning as an active therapy that requires high commitment and motivation [9].

In a study by [9], the authors conclude that the LMC is the primary haptic VR sensor for upper limb mobility recovery compared with other non-immersive VR devices, such as the Doctor Kinetic® and Nintendo® Wii game systems, which are more specialized in posture and balance. The results suggest that the LMC can be considered a valuable and effective haptic VR device to improve different aspects of upper limb motor function in neurological patients [9].
