Page 62 - Flexible Robotics in Medicine

46 Chapter 3

increase with age, we can safely approximate the nasopharynx measurements of group 4
(age 16 18) as the measurements for a standard adult.

3.2.2.4 Estimation of the distance between a nasal inlet to the nasopharynx

Another important measurement is the distance from the nasal inlet to the nasopharynx
region. The distance from the nasal inlet to the outlet (just after nasopharynx) for Asian
females is found to be 98.43 mm on average [14]. The variance in the distance of nasal
inlet to the nasopharynx region for Asian males, is approximately 90 100 mm [15].
Presently, based on the existing diagnostic nasal endoscope commonly used, the diameters
usually range from 2.7 to 4 mm [16]. The results are summarized as follows.
Based on the statistics (ethnicity, age, or gender) from the target demographic, we select
dimensions and specifications for the prototype.

3.2.3 Approach

Due to anatomical constraints, the prototype is made of only one single tube in order to
maximize the efficiency and functionality of the prototype (Fig. 3.1). Currently, due to
restrictions on the material selection and fabrication process, the existing functional
prototype is made using 95% VeroClear and 5% TangoBlack. However, the actual material
that would be employed for the prototype is polyurethane. By altering the compositions
of polyurethane, we will be able to achieve the desired mechanical properties for the
prototype. The use of polyurethane ensures the safety of the prototype, as it a
biocompatible material and FDA approved.

Additionally, the prototype provides two unique features in order to capture good viewing
images of the nasopharynx. Firstly, the endoscope tip is designed with diamond cuts to
increase the flexibility of the endoscope. This allows for large bending angles of the
endoscope tip in order to provide an extensive view of the nasopharynx region. Second, the
prototype can operate in 3 DOF, as compared to most existing prototypes with only 2 DOF.
The additional degree of motion is due to the ability to extend and retract the camera in the
axial direction, which enhances the quality of the image captured due to the mechanical
zooming of the camera.

3.2.4 Function of the prototype

FlexDiamond is a prototype that aims to aid in the surveillance for NPC recurrence, through
a minimally invasive procedure, for a minimum period of 2 years. The prototype aims to
allow the subjects to conduct nasal endoscopy by self-administering the prototype from
the comfort of their homes. The images of the nasopharynx captured will be sent to the
clinician to review and monitor their conditions. The endoscope will enter the subject’s