Department of Bioengineering BRIEF PROJECT TITLE/TOPIC (font 32) Group 101-A2 Joseph Kimmel – Background & Hypothesis Jon Wang – Methods & Protocol George Lin – Deliverables & Pitfalls Abhinav Rampuria – Equipment & Budget

Department of Bioengineering Background: Despite the advent of “staple” sutures, non-absorbable “sewn” sutures are still common-place as either staple supplements or replacements in many surgeries. Chemical environments vary in different parts of the body (e.g stomach and intestine). Therefore, it is desirable to determine relative strengths in acidic and basic environments of different suture materials. BE210 Experiment 5 has shown that it is feasible to determine relative strengths of materials by analyzing deformations in a marked digital picture. (example to right) Hypothesis: Nylon sutures will be stronger in a neutral and basic environment than in an acidic environment. Relative strengths will be determined by the longitudinal strains induced on the suture by hanging weights. Joseph Kimmel

Department of Bioengineering Methods & Protocol: Standardize pH Meter with the pH = 4, 7, & 10 standard solutions. Make 15 samples of N-wave sutures (6cm x 2.5cm). Make “+” marks 1cm above stitches, used for measurements. Ensure consistency in geometry and markings. Position wound surrogate and underwater camera in tank. With 5 trials each, fill the tank with solutions of pH = 2, 7, and 9. Position pH meter, and record pH at 30 second intervals. Set up the Camera program, and take sample shots for calibration with pictures of a ruler to determine correlation of pixel to cm. Calibrate 1kg and 2kg weights using spring scale inside the filled tank. Load sample with 1kg weight, and save picture. From pixel-cm scale, record vertical and horizontal deformation measurements. Load sample with 2kg weight and make similar measurements. Perform One-sided Two-sample T-tests assuming unequal variance comparing deformations for pH 2 to pH 7, pH 2 to 9, and pH 7 to 9. Jon Wang N stitch

Department of Bioengineering Proposed Deliverables/Findings: Potential Pitfalls: Images analyzed to find deformation (lateral and longitudinal) data Suture deformation will yield Strain data which can be used in comparison of relative strengths. Graph of force-displacement Curve for both acidic, basic, and control. Graph of pH vs elongation of suture to determine deformation at each force level. Hypothesis should be correct. Acids should reduce tensile strength. Distortion of the image in the water via Snell’s Law The webcam should correct for this since the water is uniform. Repeated sample testing takes time Corrected by testing multiple samples in parallel Changing position of samples due to repeated loading and unloading Care must be taken to ensure that the picture captures ALL of the sutures being tested simultaneously George Lin

Department of Bioengineering Equipment/Materials and Budget & Justification: 1.CIC X 480 Underwater Digital Webcam Price: $80 from gallon clear Fish Tank (20“L x 10"W x 12"H) Price: $13 from 3.HCl concentrate, 10N Price: $37 from Fisher Scientific 4.Sodium Hydroxide Concentrate, 10N Price: $43 from Fisher Scientific 5.Stack of 3 12” rulers taped together. 6.BE210 lab hooks, clamps, 1kg & 2kg weights, pH meter and nylon. 7.Block/Stand for camera Abhinav Rampuria