# Concept Justification of Future 3 DPVS and Novel Approach towards its Conceptual Development
## 3 Conceptual Design Approach for 3 DPVS
### Establishing Conceptual Design Process for 3 DPVS
#### 3.3.4 Concept Evaluation and Solution Validation  
Comparing concepts to one another needs (unchanging) criteria for evaluation. Concept evaluation is the third stage of the conceptual design, and the main objective is to evaluate the alternative conceptual solutions and select the best one as the principle solution. Hence, alternative solutions are the input of this stage and the principle solution is the output [30]. For the 3 DPVS design, this stage could include five steps. In this phase, it might also be useful to introduce concept evaluation with means such as computer simulation, CAD virtual prototyping and sample product validation by 3 DP testing. The scaffold concept needs to fulfil both the requirements of computer simulation and be feasible by 3 DP; otherwise the concept is not practical and needs to be re-generated. In brief, three key elements could constitute concept evaluation:  
* Concept evaluation through a criterion-based analytic evaluation system, for example quality function deployment (QFD);
* Evaluation with computational simulation methods for virtual testing or prototyping;
* Evaluation pf 3 DPVS primary samples or parts through 3 DP fabrication methods in reality. _Step 1: Establishing an Evaluation Criteria System for 3 DPVS Alternative Solutions_  
The principles of criteria selection state that the criteria should comprehensively reflect the design requirements and be estimated in the conceptual design phase. These identified criteria should have the capacity to reflect customer requirements of the designed 3 DPVS; so they can be selected from the attributes of the conceptual product generated in the first step of the concept generation stage. These attributes should have three characteristics. These criteria should thoroughly reflect the requirements in initiation phase. Also, they should be condensed and evaluable for alternative solutions in the conceptual design phase. Hence there cannot be too many criteria and the criteria cannot be too detailed as well. Finally, one or two criteria normally need to be selected from a set of attributes that reflects the same requirement, which could ensure the accuracy of the evaluation. For the 3 DPVS concept evaluation, 15 criteria are introduced here:  
* Design feasibility from base models;
* Functionality of being self-vibratory, partly or largely;
* Applicability of new vibration mechanism compared with traditional mechanism vibration;
* Controllability and flexibility of vibration, for example vibrating frequencies;
* Time-tailored dynamicity for cell culture;
* Affordability and usability by cell studies especially for bones;
* Safety for cells and researchers;
* Quality of geometric characterization, especially for pores;* Pore interconnectivity;
* Mechanical load-bearing capacity;
* Efficiency of cell penetration;
* Permeability of culture medium;
* Maintenance of 3D cell phenotypes (template for 3D morphology);
* Adequacy of mechanical properties;
* Desirable biocompatibility or biodegradability;
* Availability of existing smart materials or dynamic materials;
* Fabricability by 3 DP methods. After this, a criteria system is established to evaluate the conceptual solutions. Note the difference in criteria selection between conceptual and detailed design. For 3 DPVS, since it focuses on the conceptual stage and scaffold innovation, the evaluation system containing criteria that can be too specific or detailed and that will not be used. These specific criteria will generally be based on judging sub-system components, which can be introduced only in the later conceptual stage. _Step 2: Ranking Concepts by Criterion_  
This phase traditionally includes two steps, determining the weights of each criterion and calculating scores. For the nature of 3 DPVS design, this part would be rather subjective, as it is generally difficult to define which characterization of the scaffold is superior over another.