ME C178 In class sheets notes

L2 — Describe the difference between BioTech, MedTech, and HealthTech.

BioTech uses biological processes/systems to develop health-related products and technologies (e.g., drug development). MedTech provides tools for healthcare providers to diagnose or treat patients (e.g., surgical tools/robots). HealthTech provides tools directly to consumers to manage their health (e.g., at-home tests).

L2 — What are the three anatomical planes?

Sagittal, coronal (frontal), and transverse planes.

L2 — Name the four directional pairs used to describe anatomy.

Medial/lateral; proximal/distal; anterior/posterior; superior/inferior.

L2 — Identify two motion pairs and describe their movement.

Examples: flexion/extension = decrease/increase the angle between body segments; abduction/adduction = movement away from/toward the body’s midline.

L3 — Identify three physical models discussed for product/crash testing and give a major advantage/limitation of each.

Human subjects: realistic anatomy + biological response, but unsafe/unethical for injury-level testing. Human cadavers: realistic anatomy, but only passive movement and no living biological response; also costly. ATDs/crash-test dummies: repeatable and instrumented for force/displacement measurements, but only approximate selected human body types and behavior.

L3 — How do crash-test dummies (ATDs) represent human subjects?

They use anthropometric dimensions for selected body types and contain sensors throughout the body to measure quantities such as force and displacement/strain, which are used to set safety/design standards.

L3 — T/F: NHTSA evaluated vehicle safety using ATDs that represent all body types.

False. The ATD family includes selected standardized body sizes (e.g., 5th-percentile female and 50th-percentile male plus child dummies), not every body type.

L3 — How are designs tested (or not) to represent the entire population?

Testing uses a limited set of standardized anthropometric models, so it cannot fully represent population variability in body size, shape, posture, age, sex, etc. This is the 'flaw of averages' problem.

L3 — What are the automotive and aviation HIC thresholds?

Automotive: HIC ≈ 700 threshold. Aviation/FAA: HIC ≈ 1000; the lecture notes HIC > 1000 corresponds to about a 23% risk of brain injury.

L3 — What are the key variables in the Head Injury Criterion (HIC)?

Head acceleration and the duration/time interval over which the acceleration occurs (t1 to t2). Greater acceleration and/or duration increases HIC.

L4 — What are the four quadrants of the design cycle?

Observe & Notice; Frame & Reframe; Imagine & Design; Experiment & Test.

L4 — How are the four quadrants used to improve a device design?

Observe/Notice user needs → Frame/Reframe the problem → Imagine/Design possible solutions → Experiment/Test prototypes → use what you learn to repeat/reframe the cycle. Example: observe prosthetic discomfort/identity concerns, reframe the need, design a better socket or form, test it, then iterate.

L4 — T/F: Device designs go through multiple iterations on both short and long time scales.

True. The design cycle is iterative; testing and new observations feed back into reframing and redesign over both individual design cycles and historical device development.

L4 — T/F: In design, 'form' focuses on what the design does or its purpose.

False. Form is the external shape/appearance. Function is the purpose or what the design does.

L4 — T/F: If a design functions well, it will be broadly accepted universally.

False. Function alone does not guarantee adoption; form, comfort, identity, user needs, culture, cost, and other factors can affect acceptance.

L5 — What two laboratory tests assess upper-limb dexterity/function?

Southampton Hand Assessment Procedure (SHAP): assesses grip/manipulation of different-sized objects. Box and Block Test: assesses manual dexterity by moving blocks.

L5 — T/F: In a voluntary-opening prosthesis, the device is naturally in the closed position.

True. The device is closed by default and body-powered motion/tension opens it.

L5 — T/F: A voluntary-opening or voluntary-closing prosthesis must be operated using the user's other hand.

False. It is body-powered: the user moves their body to control the prosthesis; the opposite hand is not specifically required.

L5 — Identify three major challenges in mass-producing prosthetic limbs.

1) Achieving function closer to a natural limb increases complexity. 2) Mass production and cost reduction are difficult. 3) Prostheses still need fast patient-specific/custom development and fitting.

L5 — What is co-design, and how could you co-design with an older adult?

Co-design means designing with stakeholders/users rather than only for them. Use need-finding interviews/observations, let the older adult describe needs/emotions/aspirations, include relevant stakeholders such as clinicians/caregivers, prototype, obtain feedback, and iterate.

L6 — How can prosthetic-foot designs differ to increase mobility or stability?

Designs vary in material stiffness, shape/stress profile, springs/compliance, and sometimes powered ankle actuation. More compliant/spring-like designs allow deformation, shock absorption, and energy return; more rigid designs emphasize support/stability.

L6 — What materials are used in prosthetic limbs, and what are their pros/cons?

Carbon fiber: lower stiffness/more deformation and useful elastic behavior, lightweight; stainless steel: very stiff/strong but heavy; polymers: can provide shock absorption/compliance; silicone: soft/flexible for sockets and comfort.

L6 — What are limiting factors in mechanical knee designs?

The natural knee is complex, so prosthetic knees must balance stability, mobility/range of motion, load bearing, and load absorption while controlling mechanical complexity.

L6 — How are stability and mobility connected in prosthetic knees/feet?

They are a design tradeoff: greater constraint/rigidity tends to increase stability but can reduce mobility; greater freedom/compliance can increase mobility but may reduce inherent stability. Linkage geometry can help balance both.

L6 — How can prosthetic-knee designs differ to increase stability or mobility?

They can use different hinge/linkage geometries (including 4-bar linkages), springs/dampers, hydraulic elements, or microprocessor control. These choices change range of motion, stability, and load absorption.

L6 — What material wear/damage can be expected in lower-limb prosthetic designs?

The slides emphasize repeated load bearing, deformation, and moving components; therefore expect wear at joints/linkages and fatigue or degradation of repeatedly loaded springs, polymers, and compliant foot components. The lecture does not give a more specific wear-mechanism list.

L7 — In a healthy gait cycle, what percentage is stance vs swing?

About 60% stance and 40% swing.

L7 — What components can be used to assess gait biomechanics in a laboratory?

Motion-capture/physical markers, cameras/Kinects/BTS MOCAP, IMUs, force platforms, and instrumented devices such as crutches.

L7 — What limits transferring gait/motion analysis from a laboratory to the field?

Objects can block the view, people can move out of camera range, and complex/wearable equipment can interfere with normal work or activity.

L7 — What information do gait-lab markers provide?

They visually track joint/body position and movement over time; trajectories can be used to characterize movement and derive quantities such as velocity/acceleration.

L7 — What is an IMU and what information can be collected?

IMU = Inertial Measurement Unit. The lecture describes it as containing motion sensors such as a gyroscope and being used to obtain motion information such as acceleration and position/orientation; IMUs are used in wearables and smartphones.

L7 — What might an upward trend in an older adult's Double Support Time mean for gait health?

They are spending more of the gait cycle with both feet on the ground, suggesting a greater need for stability and less single-leg support. It can be associated with reduced balance/stability and age-related changes, and may also reflect reduced strength or neurological/coordination changes.

L8 — Define a brace, orthosis, and exoskeleton.

Brace: wearable external structure/device that supports an injured body part. Orthosis: wearable external device used to correct/support disorders of the limbs or spine. Exoskeleton: wearable external structure that augments, assists, or restores human movement; it may be rigid or soft.

L8 — What is the difference between active and passive exoskeletons?

Active exoskeletons use powered actuators/motors to generate assistance. Passive exoskeletons are mechanical and use elements such as springs/linkages without powered actuation, reducing weight/complexity.

L8 — Pros/cons of full-body vs single-joint exoskeletons?

Full-body: can assist multiple joints/tasks but is more complex, heavier, and harder to control/fit. Single-joint: simpler and more targeted/lightweight, but only assists a limited motion/task and can still present comfort/alignment challenges.

L8 — What actuator types can be used in an active exoskeleton?

Pneumatic (air-based), hydraulic (liquid-based), and electric/motorized actuators.

L8 — What sensors can be used in an exoskeleton and what do they measure?

EMG: muscle activity; potentiometer: joint angle; pressure sensor: ground-reaction force/pressure; gyroscope + accelerometer: torso/body orientation and motion.

L8 — T/F: Exoskeleton development was initially associated with DOD/military efforts to improve capability.

True in the lecture framing: military/DOD-supported applications aimed to augment strength, endurance, and load-carrying capacity.

L8 — What application areas were discussed for exoskeletons?

Military load/capability augmentation; workplace ergonomics/injury reduction; medical mobility assistance and rehabilitation; and spaceflight/exercise countermeasures.

L8 — Give an example of an exoskeleton application in space.

Exercise equipment that interfaces with the body and applies loads in microgravity to counter bone loss and soft-tissue/muscle degradation.

L8 — How can exoskeletons help address a physical-therapist shortage and improve rehab access?

They can complement PT work by providing repeatable mobility/rehabilitation assistance, helping serve more patients and potentially extending access to people in low-income or rural areas.

L9 — What caused the federal government to establish institutions such as the Bureau of Chemistry and FDA?

Rules varied by state, misleading health claims and food adulteration were common, science for detecting fraud/purity was improving, and the public demanded safer foods and drugs.

L9 — How did the Bureau of Chemistry determine acceptable levels/effects of certain food chemicals?

Dr. Harvey Wiley's 'Poison Squad' used controlled human feeding experiments: groups consumed measured chemicals/additives under controlled diets while effects were studied.

L9 — What two things does the FDA evaluate medical devices for before clearance?

Safety and efficacy. Safety = acceptable risk/no unacceptable harm when used as intended. Efficacy = the device works for its intended purpose.

L9 — T/F: Companies must always provide long-term data proving safety and efficacy before FDA clearance.

False. The lecture's 510(k) hip example was cleared using substantial equivalence/laboratory testing without long-term clinical outcome data.

L9 — How are medical devices classified?

By intended use, indications for use, and risk: Class I = low risk/general controls; Class II = medium risk/additional standards and post-market surveillance; Class III = high risk/life-sustaining or potential serious injury and subject to premarket approval.

L9 — T/F: When doctors/device users find a problem, the information only stays among peers.

False. The regulatory system includes reporting of device/drug complications to the FDA; manufacturers are specifically required to report complications.

L9 — What are the two main FDA pathways discussed for getting a device to market?

510(k) submission and PMA (Premarket Approval).

L9 — How do 510(k) and PMA differ?

510(k): for a 'me too' device that is substantially equivalent to an existing device; generally less extensive/costly. PMA: for novel/high-risk Class III devices and requires stronger evidence of safety and efficacy, including preclinical testing and clinical trials.

L9 — What types of devices must go through PMA?

Class III, high-risk devices—especially novel, life-sustaining devices or devices with potential for serious injury.

L10 — What three key components of the Nuremberg Code were emphasized?

1) Voluntary consent without coercion. 2) The volunteer can stop participation, and the scientist must be prepared to terminate the experiment. 3) Experimental design should be based on previous testing/evidence (lecture example: animal or cadaver testing; the lecture notes FDA changed the animal-testing requirement in 2023).

L10 — What governing body reviews experimental designs involving living humans?

An Institutional Review Board (IRB). It determines whether human-subject testing can proceed and evaluates issues such as whether benefits outweigh risks.

L10 — How many clinical-trial phases occur before FDA approval?

Three clinical phases before approval: Phase I, Phase II, and Phase III. Phase IV occurs after approval as post-market follow-up.

L10 — What is the purpose of Phase IV clinical trials?

Post-market evaluation: study long-term effects/performance in a larger population after the product is on the market.

L11 — What length scales can be used to analyze biomechanics problems in Yousuf's multiscale approach?

Cell → sub-tissue → tissue → joint → body.

L11 — What is the difference between experimental and computational research?

Experimental research directly tests/measures physical specimens and has progressed toward smaller length scales and material mechanics. Computational research uses mathematical/finite-element models and constitutive frameworks to calculate/predict 3D tissue mechanics.

L11 — What two surgical techniques for adolescent idiopathic scoliosis were discussed, and how do they differ?

Posterior spinal fusion (PSF) uses stiff rods and fused posterior bone to rigidly correct/hold the spine. Vertebral body tethering (VBT)/growth modulation uses a flexible cord to modulate growth while preserving more motion; tethering was noted as FDA-approved in 2019.

L11 — What tissue/material analogy was made for something strong in compression but weak in tension?

Cartilage was compared conceptually to reinforced concrete: water/proteoglycan behavior helps support compression while collagen provides tensile/shear strength, analogous to concrete being reinforced by rebar.

L11 — What is osteoarthritis, and why is cartilage regeneration limited?

The lecture shows untreated cartilage damage accumulating into osteoarthritis with chronic inflammation/pain and emphasizes cartilage's low self-regenerative capacity. Cartilage is avascular, mostly extracellular matrix, and has sparse chondrocytes/nutrients. (The in-class sheet says 'can regenerate,' but the lecture supports limited regeneration.)

L11 — What are Pete's three scales of validation?

Cell biology level (single-cell RNA sequencing); matrix level (collagen and glycosaminoglycan); tissue mechanics level (uniaxial unconfined compression/stress-relaxation testing).

L11 — What is spaceflight a good model for?

Musculoskeletal degradation/accelerated degeneration associated with unloading/microgravity.

L11 — What spinal component is the focus of Jo's research?

The cartilage endplate (CEP) of the intervertebral disc/vertebral interface.

L11 — T/F: Bone/endplate density decreases with spaceflight.

True in the lecture results: the flight-group cartilage endplate density was about 10% lower than the ground group, and the lecture frames spaceflight as associated with bone loss/osteoporosis.

L11 — What participant population was sent to space in Jo's research?

Mice (the RR10 cohort; C57 mice).

L12 — T/F: Veins transport oxygen-rich blood from the heart to organs and muscles.

False. Arteries generally carry blood away from the heart to the body; veins generally return blood to the heart.

L12 — T/F: The heart is a skeletal muscle that acts involuntarily.

False. The heart is cardiac muscle and acts involuntarily.

L12 — How does a heart-rate sensor measure heartbeat?

It uses PPG (photoplethysmography): an LED shines light into tissue and a photodetector measures changes in reflected/transmitted light caused by pulsatile changes in blood volume. Repeating PPG peaks correspond to heartbeats.

L12 — How does a pulse oximeter measure oxygen saturation?

It uses red and infrared LEDs and compares light absorption because oxygenated and deoxygenated hemoglobin absorb the wavelengths differently. It estimates SpO2, the percentage of hemoglobin carrying oxygen.

L12 — How does an electrical signal cause blood flow throughout the body?

Cardiac electrical depolarization activates heart muscle contraction; ventricular contraction generates pressure that pumps blood through the circulation.

L12 — What are limitations/biases of PPG measurements?

Skin tone/melanin, skin thickness, body location, sensor contact/tightness, and optical conditions can affect readings. The lecture also notes PPG heart-rate monitoring is less accurate than EKG.

L12 — What is the difference between green and red LEDs for heart-rate PPG?

The lecture states green LEDs provide more reliable/consistent data, while red LEDs are more efficient. Blood absorbs green light and reflects more red light.

L12 — What happens to blood supply when a vessel is constricted by plaque buildup?

Atherosclerotic narrowing restricts blood flow; severe narrowing/clotting can reduce or cut off downstream blood supply.

L12 — How can restricted blood supply affect heart-rate readings from a PPG?

Because PPG depends on pulsatile blood-volume changes, reduced peripheral blood flow can weaken the optical pulse signal and make readings less reliable/noisier.

L12 — What can impact the ability to measure heart rate using a PPG sensor?

Skin tone, skin thickness, sensor location, sensor contact/tightness, movement/optical interference, and the strength of local blood perfusion.

L12 — What type of muscle is the heart?

Cardiac muscle.

L12 — From the Heart Rate Lab, what further questions could be explored?

Examples consistent with the lecture's experiment-design prompt: effects of sensor location, exercise/activity, sensor tightness, skin properties, movement, or comparison of PPG with a reference method.

L12 — What variables could impact the QRS curve?

Changes in ventricular electrical activity/conduction can alter QRS amplitude, duration, and shape; arrhythmias or heart damage can therefore change the QRS waveform.