## 6 Conclusions  
The immersive technologies, most typically referred to as virtual reality (VR) and lately also to include augmented reality (AR) enabling technologies, are popularly researched and developed to improve healthcare and treatments for physical, psychological and social wellbeing with respect to different populations and their health issues (e.g., elderly, autism spectrum disorder, PTSD, phobia, etc.) [26; 27]. For example, [PERSON] et al. [24] have comprehensively reviewed VR and AR technologies developed for physical, psychological and social wellbeing of an elderly population. The review article discovers that plenty of R&D has been deployed for improving physical healthcare and treatments. Nonetheless, considering the rising psychological (mental and social) health issues, there are great needs to pursue immersive technologies and design immersive solutions for psychological therapies and treatments. The research presents the systematic design and development of virtual reality exposure therapy applied to fear of driving. Therapeutic treatments for this phobia remain as a major clinical challenge for psychiatrists, psychotherapyists, and their patients. A VR headset, a high specification steering wheel, bio-sensors, and software are integrated to develop a realistic driving experience in an immersive environment for effective exposure therapy. The subjects are exposed to varying levels of fear inducing driving levels for treatment. Thirty subjects provided pre-test data for the system. The bio-feedback data and suggestions for improvement were derived from the experiments. Through pre-test data analysis, VR convincingly causes anxiety like actual driving. Furthermore, some systemic problems are discovered, so the follow-up research can improve the VRET system and improve the system design. Carefully crafted experimental design is required for collecting valid and reliable data for the VRET analytical models and system modification. The clinical psychiatrists' feedback is critical to improve the design before the VRET can be used for clinical trials.  
In summary, this research has presented the VRET technical components, the system framework, key modules for implementation, and the experiment database design and development for the research. Specifically, the bio- and system-data analysis demonstrates the efficacy of the VRET for use in initial hospital-based clinical trials with continued improvement as the trails are analyzed. In the future, the research team hopes to extend the VRET treatments to other phobias, such as acrophobia, arachnophobia, and claustrophobia. The future research direction also includes the intelligent development of self-adaptive VRET systems incorporating progressive brain neurology and brain computer interface (BCI) technologies. When the degree of a subject's fears are detected through advanced BCI sensors, the self-adaptive VRET system will have sufficient knowledge and intelligence to automatically adjust the levels of exposure to ensure safe and effective gradual systematic desensitization.  
A.T.: Constructed the research framework and incorporated VR and IoT technologies for the system; C.V.T.: CBT and ET literature overview for anxiety disorders and panic disorders, interpretation of meta-analysis studies; C.-M.C.: PTSD, OCD, and PD theories and clinical ET design; R.R.T.K.: VRET system development and implementation, data analysis; A.P.C.L.: VR and VRET literature search, VRET prototype testing, data validation; C.H.N.: CBT and ET literature review and data validation. All authors have read and agreed on the published version of the manuscript.  
**Funding:** This research is partially supported by the joint research grant of National Tsing Hua University and Chang Gong Memorial Hospital and the individual research grants of Ministry of Science and Technology, Taiwan (Grant numbers: MOST-108-2221-E-007-075-MY3 and MOST-108-2410-H-009-025-MY2).  
**Conflicts of Interest:** The authors declare no conflict of interest.