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Validation of a roughness parameters for defining surface roughness of prosthetic polyethylene Pe-Lite liner

Hamzah NA, Razak NAA, Karim MSA, Salleh SZ

Sci Rep, 2022 Feb 16;12(1):2636.
PMID: 35173198 DOI: 10.1038/s41598-022-05173-3

The Biosculptor's CNC milling machine, the Biomill, offered four different surfaces machined on positive models. This study aims to adopt the surface topography method in characterizing the four different surface roughness of polyethylene Pe-Lite liner as a product of the Biomill. Three surface parameters chosen were the arithmetic average (Ra), root mean square roughness (Rq), and ten-point height (Rz). The surface parameters were used to define the four different surfaces (STANDARD, FINE, COARSE, and FAST) and then compared with the same liner material from a conventionally fabricated socket. The Ra values of the conventional liner, 8.43 μm, were determined to be in-between the Ra values of STANDARD and FAST surfaces which were 8.33 μm and 8.58 μm respectively. STANDARD surface required 43.2 min to be carved while FAST surface took almost only a third of the time compared to STANDARD surface (conventional socket takes 2-3 days). The results of this study would be one of the guidelines to the prosthetists using the Biosculptor in socket fabrication to produce sockets according to the suitable surface to cater to different requirements and levels of activity of each amputee.
Comparative study on the accuracy of Biosculptor's Bioscanner system in transtibial residual limb circumference measurement

Hamzah NA, Razak NAA, Karim MSA, Salleh SZ

Acta Bioeng Biomech, 2021;23(4):173-182.
PMID: 37341100

PURPOSE: This study aimed to examine the accuracy and validity of the Biosculptor's Bioscanner shape capturing system as a portable measuring device by analysing the changes in transtibial residual limb circumference parameters while walking. Assessment on an amputee could also allow for the clinical usability of the digital scanner to be studied.
METHODS: To verify the accuracy of the system, the Bioscanner method was compared to the widely used standard anthropometric manual measurement technique (i.e., tape measure). One transtibial prosthetic user was recruited to conduct a walking activity at a normal walking pace for 5 to 15 minutes. Circumferential profiles of the participant were obtained digitally and manually during 2-5 minutes of resting walking intervals. The mean differences between the two methods were compared and percentage differences were calculated. The means were used to calculate the standard error measurement (SEM) and the 95% confidence intervals. Study of the limit of agreement between the two method was also used to validate the accuracy of Bioscanner.
RESULTS: The findings showed that both measurements gave a general comparable linear pattern. The averaged results from both methods resulted in only small distinctive differences especially at circumference near the mid-patella tendon. Similarly, the pressure-sensitive areas of the limb resulted in only an average of 2.28% differences between the two measurement techniques. The system showed high reliability and SEM with <1 of 95% CI values and repeatability study gave ICC >0.9.
CONCLUSIONS: Bioscanner appeared to be comparable with the standard manual method. The Biosculptor system provides the portability, fast, reliable, and high accuracy measurements of the transtibial residual limb circumference, thus, it can be considered as a valuable tool for daily measurement of amputee's residual limb and pre-prosthetic training.
Properties and Performance Verification on Magnetite Polydimethylsiloxane Graphene Array Microwave Sensor

Jamlos MA, Jamlos MF, Alias A, Karim MSA, Mustafa WA, Akkaraekthalin P

Polymers (Basel), 2021 Sep 24;13(19).
PMID: 34641072 DOI: 10.3390/polym13193254

This paper investigates the use of a Magnetite Polydimethylsiloxane (PDMS) Graphene array sensor in ultra-wide band (UWB) spectrum for microwave imaging applications operated within 4.0-8.0 GHz. The proposed array microwave sensor comprises a Graphene array radiating patch, as well as ground and transmission lines with a substrate of Magnetite PDMS-Ferrite, which is fed by 50 Ω coaxial ports. The Magnetite PDMS substrate associated with low permittivity and low loss tangent realized bandwidth enhancement and the high conductivity of graphene, contributing to a high gain of the UWB array antenna. The combination of 30% (ferrite) and 70% (PDMS) as the sensor's substrate resulted in low permittivity as well as a low loss tangent of 2.6 and 0.01, respectively. The sensor radiated within the UWB band frequency of 2.2-11.2 (GHz) with great energy emitted in the range of 3.5-15.7 dB. Maximum energy of 15.7 dB with 90 × 45 (mm) in small size realized the integration of the sensor for a microwave detection system. The material components of sensor could be implemented for solar panel.
Fulltext Surface profile analysis of laminated transfemoral prosthetic socket fabricated with different ratios of epoxy resin and acrylic resin

Zainuddin NAMN, Razak NAA, Karim MSA, Osman NAA

Sci Rep, 2023 Feb 15;13(1):2664.
PMID: 36792914 DOI: 10.1038/s41598-022-21990-y

Acrylic and epoxy are common types of resin used in fabricating sockets. Different types of resin will affect the internal surface of a laminated socket. This paper is to determine the best combination of ratio for epoxy and acrylic resin for a laminated prosthesis socket and to evaluate the surface profile analysis of different combinations of laminated prosthetic sockets for surface roughness. Transfemoral sockets were created using various resin-to-hardener ratios of 2:1, 3:1, 3:2, 2:3, and 1:3 for epoxy resin and 100:1, 100:2, 100:3, 100:4, and 100:5 for acrylic resin. Eight layers of stockinette consisting of four elastic stockinette and four Perlon stockinette were used. A sample with a size of 4 cm × 6 cm was cut out from the socket on the lateral side below the Greater Trochanter area. The Mitutoyo Sj-210 Surface Tester stylus was run through the sample and gave the Average Surface Roughness value (Ra), Root Mean Square Roughness value (Rq), and Ten-Point Mean Roughness value (Rz). Epoxy resin shows a smoother surface compared to acrylic resin with Ra values of is 0.766 µm, 0.9716 µm, 0.9847 µm and 1.5461 µm with 3:2, 3:1, 2:1 and 2:3 ratio respectively. However, for epoxy resin with ratio 1:3, the resin does not cure with the hardener. As for acrylic resin the Ra values are 1.0086 µm, 2.362 µm, 3.372 µm, 4.762 µm and 6.074 µm with 100: 1, 100:2, 100:5, 100:4 and 100:3 ratios, respectively. Epoxy resin is a better choice in fabricating a laminated socket considering the surface produced is smoother.