Bioengineering Fundamentals

Citation

Saterbak, A., San, K.-Y., & McIntire, L. V. (2017). Bioengineering Fundamentals (2nd ed.). Pearson.

Chapter Summary

The book has seven chapters (about 620 pages in the second edition) and five appendices: a list of symbols, unit conversion factors, a periodic table, tables of biological data and thermodynamic data. Pearson presents it for sophomore-level courses in bioengineering and biomedical engineering. It grew out of a manuscript the authors wrote and class-tested at Rice University, Georgia Tech and Washington State University, first titled Conservation Principles in Bioengineering; the first edition appeared in 2007. The authors described the manuscript's chapters in detail in two papers for the American Society for Engineering Education (ASEE, 2004 and 2006); the summaries below draw on those descriptions, which predate the published editions, and on Pearson's account of the second edition. For the second edition, Pearson says denser sections were expanded mainly in Chapters 3–5, worked examples were added throughout Chapters 1–6, and new homework problems, including computational ones, were added to all chapters.

Chapter 1: Introduction to Engineering Calculations

Reviews units, dimensions and unit conversion, and distinguishes intensive from extensive variables, the ones that can be counted in a conservation law. In the authors' description, about thirty physical variables are introduced through short bioengineering scenarios (drug delivery, gene transfer, a microsurgical assistant and others). The chapter also sets out the four-step problem-solving method used for most worked examples in the book: assemble, analyse, calculate, finalise.

Chapter 2: Foundations of Conservation Principles

Sets up the framework for the rest of the book: defining a system, its boundary and surroundings; the accounting equation (input − output + generation − consumption = accumulation) and its special case, the conservation equation; algebraic, differential and integral forms; and the classification of systems as open or closed, steady-state or dynamic, reacting or non-reacting.

Chapter 3: Conservation of Mass

Applies the framework to mass, opening with a tissue-engineering challenge on bone replacement. It moves from steady-state, non-reacting open systems to multiple inlets and outlets, multicomponent mixtures, multi-unit systems such as a two-compartment kidney model, reacting systems (with reaction rate and fractional conversion) and dynamic systems such as drug delivery.

Chapter 4: Conservation of Energy

Defines kinetic, potential and internal energy and enthalpy, and the transfer of energy as heat and work. Balances are worked first for closed systems, then for open steady-state ones, with considerable attention to calculating enthalpy changes due to temperature, pressure, phase change and reaction (examples include respiration). Dynamic examples include bioreactor start-up and the use of basal metabolic rate to estimate weight gain.

Chapter 5: Conservation of Charge

Derives Kirchhoff's current law from the conservation of charge and develops an electrical energy accounting statement leading to resistance and Kirchhoff's voltage law. Circuit examples are joined by reacting systems (radioactive decay, acid–base dissociation, electrochemical reactions) and dynamic systems such as capacitor charging; the opening challenge concerns neuroprosthetic devices.

Chapter 6: Conservation of Momentum

Develops conservation of linear momentum, opening with the mechanics of cycling. It derives rigid-body and fluid statics, treats collisions, steady flowing systems (such as flow through a total artificial heart) and dynamic systems leading to Newton's second law and the impulse–momentum theorem. Bernoulli's equation is introduced from the mechanical energy balance, with friction losses and shaft work; angular momentum is reviewed briefly.

Chapter 7: Case Studies

Three integrative case studies that combine mass, energy, charge and momentum: the heart and blood circulation, the lungs and a heart–lung bypass machine, and the kidneys and dialysis. In the manuscript each case study came with physiological background, worked examples and open-ended homework problems requiring outside research.

Key Concepts

Chapters 1–2: Calculations and Framework

• Extensive and intensive variables: quantities that scale with the size of a system (mass, energy, charge, momentum) and those that do not (temperature, concentration); only the former can be counted in an accounting equation.
• Accounting equation: input − output + generation − consumption = accumulation, the single relation from which the book's balances are built.
• Conservation equation: the special case for a conserved quantity, which cannot be generated or consumed.
• System classification: open or closed, steady-state or dynamic, reacting or non-reacting, which determines which terms of the equation survive.

Chapters 3–4: Mass and Energy

• Mass balances on multicomponent and multi-unit systems: tracking each species through networks of units, including compartment models of organs.
• Reaction rate and fractional conversion: describing how much of a species a reaction consumes or produces.
• Enthalpy and heats of reaction: calculating energy changes due to temperature, phase and chemical reaction.

Chapters 5–7: Charge, Momentum and Integration

• Kirchhoff's laws as balances: the current law as conservation of charge and the voltage law as an energy statement.
• Linear momentum balance: the source of statics, Newton's second law and the impulse–momentum theorem.
• Bernoulli's equation with friction loss: a mechanical energy balance for flowing systems.
• Integrated physiological case studies: applying all four balances to the heart, lungs and kidneys.

Critical Analysis

Strengths

• One framework for everything. The whole book rests on the accounting equation applied to four extensive properties, so students learn one method and see that Kirchhoff's laws, Newton's laws and Bernoulli's equation follow from it. The authors designed the book this way, adapting the approach of the Texas A&M Conservation Principles and the Structure of Engineering to biological and medical examples.
• A taught problem-solving method. A four-step procedure introduced in Chapter 1 is used for most worked examples, and each chapter states learning objectives. Pearson highlights detailed worked examples that show how to turn a written problem statement into a diagram.
• Biologically relevant examples. Examples and problems span physiology, biochemistry, tissue engineering, biotechnology and instrumentation, with real numerical parameters, and each of Chapters 3–6 opens with a current research or design challenge.
• Flexible and well stocked. Pearson describes the chapters as self-contained, so a course can stress one or two properties or adopt a problem-based format; the second edition increased the number of homework problems and added computational ones.

Limitations

• Narrow by design. The book teaches conservation principles, not a survey of the field: there are no chapters on biomaterials, imaging, biomechanics as a discipline, or ethics. Students wanting an overview of biomedical engineering need another text alongside.
• Prerequisites. The authors recommend college calculus, general chemistry, physics and biology, plus basic computational skills.
• Case studies and challenge problems were the weakest elements in early testing. In the authors' own 2004 survey of Rice students using the manuscript, homework problems and worked examples were rated the most effective materials and the challenge problems and case studies the least. The published editions may have changed this, but instructors should plan how to use Chapter 7 actively rather than as reading.
• Momentum is lighter than mass and energy. In the authors' outline, angular momentum is only reviewed briefly and flowing systems are handled with Bernoulli's equation and friction-loss terms rather than with the differential equations of fluid mechanics; later transport and biomechanics courses take this further.

Where It Fits in the Course

Among the books for an introduction to biomedical engineering, this is the one built around a single method. Enderle and colleagues' Introduction to Biomedical Engineering is a broad survey of the field's subdisciplines (modelling, anatomy and physiology, electrical engineering, biomechanics, biomaterials, ethics); Saltzman's Biomedical Engineering: Bridging Medicine and Technology builds the field outward from molecular, cellular and physiological biology. Either can be read alongside Saterbak, San and McIntire to give the breadth that this book deliberately leaves out, while this book supplies the quantitative balance skills the surveys only touch on.

Ritter and colleagues' Biomedical Engineering Principles is another introductory text that emphasises quantitative analysis and engineering design, and can serve as a second source of worked material. Hobbie and Roth's Intermediate Physics for Medicine and Biology and Wittrup and colleagues' Quantitative Fundamentals of Molecular and Cellular Bioengineering are more demanding texts for later years: the first applies physics across physiology and medical imaging, the second develops models of binding, kinetics and cell behaviour. Both assume the balance-writing skills this book teaches.

How to Use This Book

The book is meant for students in their second year of bioengineering or biomedical engineering, moving from general science and mathematics to engineering courses. Students should be comfortable with first-year calculus, chemistry and physics; some biology helps with the examples.

A practical plan for one semester:

• Core: Chapters 1 and 2 thoroughly, since the vocabulary of systems and the accounting equation is used everywhere. Then Chapter 3 (mass), the longest and most important for later transport courses.
• Choose by programme: Chapter 4 (energy) for students heading towards bioprocess and transport, Chapter 5 (charge) for instrumentation and neural engineering, Chapter 6 (momentum) for biomechanics and fluids. Because the chapters are self-contained, a course can cover two or three of them in depth rather than all four lightly.
• Integration: finish with one or two case studies from Chapter 7, worked as group projects rather than read passively.

Use the four-step method on every homework problem, even easy ones: draw the system, state the assumptions and decide which terms of the accounting equation vanish before calculating. Compare the parallel structure of the four balances in a one-page summary sheet; seeing that the same equation governs mass, energy, charge and momentum is the main thing the book is designed to teach.