Biomedical Instrumentation Questions and Answers – Microelectrodes

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This set of Biomedical Instrumentation Multiple Choice Questions & Answers (MCQs) focuses on “Microelectrodes”.

1. Which type of electrodes are employed to study the electrical activities of individual cells?
a) milli-electrodes
b) micro-electrodes
c) surface-electrodes
d) pre-jelled electrodes
View Answer

Answer: b
Explanation: To study the electrical activities of individual cells, micro electrodes are employed. This type of electrode is small enough with respect to the size of the cells. Typical micro electrodes have tip dimensions ranging from 0.5-5 microns.
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2. Glass micro-capillaries are a type of micro electrode.
a) True
b) False
View Answer

Answer: a
Explanation: Two types of micro electrodes are generally used: metallic and glass microcapillaries. Metallic electrodes are formed from a fine needle of suitable metal drawn for a fine tip. Glass electrodes are drawn from Pyrex glass of special grade.

3. Glass microcapillaries are preferred over metallic electrodes because of the former _______
a) polarizes with input current
b) does not have sustainable current carrying capacity
c) has less contact surface area
d) has sustainable current carrying capacity
View Answer

Answer: d
Explanation: Metallic electrodes polarize with smaller amplifier input currents. Hence, they tend to develop unstable electrode offset potential and are therefore not preferred for steady state potential measurement. On the other hand, in case of glass micro electrodes have a sustainable current carrying capacity because of the large surface area between the metal and the electrolyte.
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4. Do metallic micro electrodes exist.
a) True
b) False
View Answer

Answer: a
Explanation: Two types of micro electrodes are generally used: metallic and glass microcapillaries. Metallic electrodes are formed from a fine needle of suitable metal drawn for a fine tip. Glass electrodes are drawn from Pyrex glass of special grade.

5. Metallic micro electrodes have impedance ________ compared to conventional electrodes?
a) equal
b) smaller
c) high
d) very high
View Answer

Answer: d
Explanation: The very high impedance of the metal micro-electrodes is due to the characteristics of the small area metal-electrolyte interface. Because of very high impedance of micro electrodes, amplifiers with extremely high input impedance are required to avoid loading the circuit and to minimize the effects of small change in interface impedance.
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6. Which of the following electrode is manufactured by circumferential application of heat to a small area of glass tubing and pulling the glass when it gets soft?
a) macro metallic electrodes
b) micro metallic electrodes
c) micro pipette
d) surface electrodes
View Answer

Answer: c
Explanation: The most commonly used method for making small tip micropipette consists of the circumferential application of heat to a small area of glass tubing which is placed under some initial tension. When the glass softens, the tension is increased very rapidly and the heat is turned off. Proper timing, controlled adjustment of the amount of heat as well as the initial and final tensions and cooling results in the production of microcapillaries with control dimensions.

7. Which of the following metal is preferred for manufacturing micro electrodes?
a) Stainless steel
b) Tungsten
c) Iron
d) Copper
View Answer

Answer: b
Explanation: Tungsten is preferred for constructing micro-electrodes due to its mechanical strength and its apparent inertness. Although tungsten itself is reactive, a surface layer of tungsten oxide will, in most situations, protect the metal against corrosion.
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8. ________________ are devices which convert one form of energy into another.
a) transducers
b) electrodes
c) impulses
d) opamp
View Answer

Answer: a
Explanation: Transducers are devices which convert one form of energy into another. A number of factors decide the choice of a particular transducer to be used for the study of a specific phenomenon. Many physical, chemical and optical properties and principles can be applied to construct transducers for applications in the medical field.

Sanfoundry Global Education & Learning Series – Biomedical Instrumentation.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter