# A Pneumatically-Actuated Mouse for Delivering Multimodal Haptic Feedback
## 1 Introduction  
The computer mouse is one of the most widely used devices for interacting with a computer. It is primarily used as an input device for interacting with visuals displayed on a computer screen--diagrams, pictures, graphs, etc. The computer mouse is a handheld (haptic) device, but the output or feedback made by it is, in most cases, visual or aural. A user only perceives the passive feedback of holding the mouse in their hands instead of acquiring rich and diverse feedback that would be provided when interacting with real objects. This uneven fidelity on different modalities in the interaction may result in the decrements of the efficiency and intuitiveness of interaction [1]. To remedy this, this paper focuses on a computer mouse providing a holistic haptic feedback for providing a rich virtual experience to the interactor. This is in particular beneficial to the visually impaired who rely heavily on their sense of touch. During haptic interaction, humans use both tactile and kinesthetic information [2; 3]. The tactile sense deals with texture, pressure, and lateral forces on the skin, while the kinesthetic sense handles the perception of stiffness, motion, and normal and rotational forces. In order for a haptic display to exhibit a holistic perception of a virtual object, it needs to provide both kinds of haptic informationin physically correct form [4; 5]. Combining this rich feedback with the most common interface, i.e., computer mouse, would maximize the positive effect of this holistic haptic experience. Various haptic devices have been designed to provide different kinds of haptic feedback. Most of these devices offer only a single kind of haptic feedback, i.e., any one of tactile feedback, force feedback, and thermal feedback. Tactile feedback is generally provided using pin arrays, voice coil actuators, or linear resonant actuators, etc. [6; 7]. Force feedback is delivered using pneumatic actuators, or motors, etc. [8; 9; 10]. Thermal feedback is usually implemented using peltier, piezoelectric, or microfluidic elements (haptx), etc. [11; 12]. The advantage of using a single mode of feedback is that the form factor of the device can be compact, as it houses a single type of actuator. The downside is the lack of other modes of feedback to create a holistic haptic experience. On the other hand, certain devices do offer multi-mode haptic feedback [13; 14]. These deploy a combination of the above mentioned elements for generating various modes of feedback concurrently. The multi-mode devices can provide a richer haptic experience by incorporating more than one kind of haptic feedback. However, the provision of each type of feedback adds an additional module or end-effector which adds to the form factor and complexity of the device. A higher number of modalities may result in a bigger device with multiple end-effectors, which may interfere with the normal haptic experience. Another shortcoming that can be related to both types of devices is the variability in their structure. In terms of devices used for interacting with computers, most come in unique forms and shapes. It requires a user to get accustomed to the device itself before it can provide a satisfactory haptic experience. Furthermore, a majority of them tend to target a certain location of the hand, i.e., mostly the finger tips. The current paper aims at a haptic system capable of providing multi-mode feedback with single actuator to the user's whole hand. To this end, we propose a pneumatically-controlled, silicone-based haptic mouse capable of providing multi-mode haptic feedback using a single end-effector, as shown in Figure 1. The dome of the mouse is made from flexible and lightweight silicone which allows efficient pneumatic control. It consists of two distinct layers, i.e., a stretchable layer and a non-stretchable layer.