Course: ENGN1230 – Bioinstrumentation Design

 

Designation: Required for BME, Bioelectrical, Biomechanical

 

Instructor: Professor J.D. Daniels; for 2013 there were 38 students in the class and the instructor was aided by 6 undergraduate TAs, 3 grad student TAs (each 6 hr/wk) and one machinist (Paul Waltz), half time. 

Course Description:  Instrumentation topics of interest to biomedical engineers, from sensors to computer data acquisition.  Sensors: including strain gauges, thermocouples, microphones, phototransistors, electrodes for nerve cell signals.  Amplifiers: op amps, instrumentation amplifiers and particularly isolation amplifiers.  Filters.  Frequency Analysis: A-D conversion and the sampling theorem; aliasing; windows for smoothing data; Statistical analysis: binomial distribution; Poisson distribution and Katz’ confirmation of quantal release at NMJ. The t-test of samples from populations of unknown stats. Use of an iconic data flow language LabVIEW for designing “virtual instruments.” Electrical safety and noise reduction; design of ground fault interruptors and defibrilators. Rotating machinery as motors, generators (tachometers) and electrical brakes. Automatic control and the role of sensory feedback; PID controllers; neural networks and fuzzy logic.

 

Lectures, Laboratory exercises, contract grading.

 

Website: http://www.brown.edu/Departments/Engineering/Courses/En123/index.html

 

Prerequisite:  Engineering core, including Electricity and Magnetism, and Differential Equations. 

 

Text: none required; online lectures notes and power point slides provided. 

 

Class Schedule: MWF 10-10:50 lectures, and self-scheduling of about 8 hours per week in lab; one “guaranteed appearance hour” per week. 

 

Topics:
* Review of basic circuits course: Resistance, Capacitance, Inductance, Transistors; node admittance matrix method of solving KCL equations

* Creating and meeting specifications for a project

* Trade-off between sensitivity and range in design of sensory systems

* Sensors for electromagnetic radiation (ultraviolet, visible light, and infrared)

* Amplifiers: op amp circuits, input impedance, GBWP, CMRR

* LabVIEW DAQ software: front panel and block diagram; NI DAQmx and 6024E PCI card specs

* Electrical safety, ground, shielding and noise: dangers of electrical current; GFI design; defibrillator design; radiation dangers

* Design of LP and HP VCVS filters; digital filters in LabVIEW; combining LP and HP for bandpass and band-reject filters

* Temperature sensors: platinum standard; thermistors (self-heating and in a Wheatstone bridge), thermocouples; IR heat sensors; liquid crystals

* Strain gauges; converting strain gauge amplifier output back to Young’s modulus of underlying material

* Analog-to-digital conversion; successive approximation, flash and dual slope converters

* Sampling Theorem, FFT, minimum resolvable frequency, aliasing

* Hypothesis testing: statistical analysis of data; binomial distribution; ethics of handling false positives in biomedical testing

* Poisson distribution: application to quantal nature of synaptic transmission

* Electrodes for recording from electrical signals from tissue: EMG, EKG

* Electrochemistry: chemical reactions at the metal-aqueous interface

* Nernst equation; cable equation for signal propagation in dendrites and axons

* Hill’s equation for Tension-Velocity curves of active muscle

* Negative Feedback and Automatic Control: PID control; stability

* Rotating machinery: motors, generators and electrical braking; generators as tachometers

* Motor torque-speed curve compared to muscle

* Wireless telemetry: design of 900MHz transmitters and receivers for robot control

 

Design projects: (not all projects required to pass the course)
* Window discriminator designed with LabVIEW
* Phototransistors designed into detector of orientation w.r.t. distant light source
* Design of system for sensing and reacting to contact with a wall, for wheelchair safety use
* Design with thermistors for Wheatstone bridge system measuring heat gun output or stirred cold water temperature unknowns
* Design and build a strain gauge system for measuring bending moment of a fiberglass crutch leg
* Design microdrive advance system for probing the sensitivity of blaberus leg spines to mechanical deflection

* Design a system of two potentiometers to test the hypothesis that in-phase bimanual knob rotation can be done at a higher frequency that alt-phase rotation

* Design a method, using a stepping motor, for automatic measurement of frog gastrocnemius muscle active length-tension curve (bell-shaped)

* Using small fan as a tachometer, design method to keep air flow constant by controlling an auxiliary fan in series with an “unstable” air flow source

* Design a system using a stationary tandem bike to demonstrate Hill’s hypothesis that muscles doing “negative” work are stronger than “positive” muscle fibers

* Design on paper a combination of VCVS LP or HP subfilters that meet specs for a bandpass or band-reject filter

 

Writing assignments: ENGN1230 is an official WRIT course at Brown University, meaning that each student enrolled must write two essays that are marked up by the instructor and revised by the student. In the case of ENGN1230, essays are based on themes of ethical decisions in research and testing of biomedical products.

 

ENGN1230 addresses ABET outcomes  (a), (b), (c), (d), (e), (f), (g), (h), (j), (k)

 

Course Goals:  On completion of ENGN1230, each student shall

 

1.      Be able to interpret and formulate design specifications for instrumentation systems that meet accuracy and sampling speed requirements. Be familiar with computer-aided design software such as LABVIEW.

2.      Understand the principles of operation of sensors including thermocouples, strain gauges (including Wheatstone Bridge circuits) and chemical electrodes.

 

3.      Understand principles of analog and digital signal and data processing, including amplifiers, filters and A-D conversion techniques.  Understand sources and measures of error in instrumentation systems, including noise and aliasing; common-mode rejection ratio of differential amplifiers; the sampling theorem and its application.

 

4.      Be able to use appropriate statistical techniques to measure the significance of results obtained from instrumentation systems.

                     
5.  Be familiar with safety issues concerning design of instrumentation, including the effects of electric AC current passing through tissue.
      Understand ground fault interruption and defibrillation.

 

Course Improvements (2008-2013):
1. Add “guaranteed weekly appearance time” to the duties of each student team, to insure consist instructor contact on a one-on-one basis.

 

2.  Include more supported lab experience: we have added labs on (a) quadrature sensing of rotation; (b) CO2 and O2 sensing of exhaled breath; (c) video microscopy for watching a microdrive probe move a blaberus spine (d) wireless telemetry using XBee transmitter-receiver pairs (e) adding a lab that uses accelerometers and gyros to sense orientation of objects held by subjects in a “Necker Cube” lab. These new labs help cover lecture topics more thoroughly.

 

3. Remove “Lab Report” requirement so students have time to perform more hands-on lab exercises; replace lab reports with specific writing assignments the instructor critiques more thoroughly, with more focus on the writing itself, instead of its technical content.

 

4. Involve on a 3-hour-per-day basis Senior Technical Assistant Paul Waltz in the course, as a person who can repair equipment expeditiously, and design new setups (e.g. the frog muscle stretcher, for Lab LT), freeing the instructor for more direct contact with students in the lab.

 

5. Improve the Basic Circuits Tutorial section of the course website; better to replace information from a circuits course not required for students in some tracks of the BME concentration.

 

6. Further refine the grading contract so as to limit the maximum number of A’s in the course to 55% of the enrolled students.

 

Professional Component: 75% Design, 25% Engineering Science