Mock quiz created by claude

You are fabricating a microfluidic device for long-term cell culture studies involving small-molecule drug treatments. Which of the following is the most significant drawback of using PDMS-based replica molding?

A) It requires a cleanroom facility B) PDMS can absorb small molecules, potentially altering cellular responses C) PDMS is optically opaque, limiting imaging D) It is incompatible with oxygen plasma bonding

B PDMS can absorb small molecules, potentially altering cellular responses

A researcher wants to mass-produce microfluidic chips for a low-cost point-of-care diagnostic at high throughput. Which fabrication method is most appropriate?

A) Injection moulding of thermoplastics B) Electron beam lithography C) Replica molding with SU-8 and PDMS D) Soft lithography with PMMA

A Injection moulding of thermoplastics

A biosensor loses activity after repeated use and shows inconsistent readings when sample pH fluctuates between 6.5 and 7.5. Which biosensor type is most likely being used?

A) Nucleic acid biosensor B) Antibody biosensor C) Nanozyme biosensor D) Enzyme biosensor

D Enzyme biosensor

You need to detect a respiratory pathogen directly from a patient's saliva in a low-resource setting without lab equipment. Which detection strategy is most appropriate?

A) PCR-based nucleic acid amplification in a thermocycler B) Smartphone-based immunoagglutination via capillary flow C) CRISPR-Cas12 with fluorescent reporter in a cleanroom device D) Organ-on-a-chip replication of airway tissue

B Smartphone-based immunoagglutination via capillary flow

Which of the following best describes the advantage of theranostic nanoparticles over conventional drug delivery?

A) They eliminate the need for imaging entirely B) They combine drug delivery and imaging to allow real-time monitoring of drug release and efficacy C) They are faster to manufacture than traditional pharmaceuticals D) They target only cardiovascular biomarkers

B They combine drug delivery and imaging to allow real-time monitoring of drug release and efficacy

A lab wants to detect a specific DNA sequence from a pathogen without a thermocycler. Which biosensor approach is most appropriate?

A) PCR-based DNA biosensor B) CRISPR-Cas12 biosensor C) Isothermal amplification integrated device D) Enzyme-linked immunosorbent assay

C Isothermal Amplification

An antibody biosensor uses Fab fragments rather than whole antibodies on a gold electrode surface. What is the primary reason for using Fab fragments?

A) Fab fragments are cheaper to synthesize B) Fab fragments allow sensing of antigen-antibody interactions without steric interference from the full antibody C) Whole antibodies cannot bind to gold electrodes D) Fab fragments have higher thermal stability than whole antibodies

B fab fragments allow sensing of antigen-antibody interactions without steric interference from the full antibody

Which of the following best explains why organ-on-a-chip devices are preferred over static cell cultures for disease modeling?

A) They are cheaper and easier to fabricate B) They better replicate disease states and cell-to-cell signaling C) They eliminate the need for biosensors D) They allow high-throughput injection moulding

B They better replicate disease states and cell-to-cell signaling

A blood sample is being analyzed for early cardiovascular disease detection using a microfluidic device. Which of the following best justifies using microfluidics over traditional diagnostic equipment?

A) Microfluidics can detect biomarkers not found in blood B) Microfluidic devices do not require patient samples C) Traditional devices cannot detect blood-borne biomarkers D) Microfluidics offers portability, fast analysis, and low reagent consumption

D Microfluidics offers portability, fast analysis, and low reagent consumption

During cryopreservation of a cell sample, significant cell death is observed post-thaw. What are the two most likely causes?

A) UV exposure and PDMS absorption B) pH instability and antibody degradation C) Osmotic shock and ice crystal formation D) Enzyme immobilization failure and PCR inhibition

C Osmotic shock and ice crystal formation

A researcher needs to immobilize an enzyme onto a biosensor surface without disrupting its active site. Which approach best satisfies this requirement?

A) Covalent bonding that targets the active site directly B) Enzyme immobilization using bonding that preserves the essential structure of the enzyme C) Dissolving the enzyme in PDMS before curing D) Attaching the whole enzyme via its Fab fragment

B Enzyme immobilization using bonding that preserves the essential structure of the enzyme

A CRISPR-based microfluidic biosensor is being used to detect a viral nucleic acid target. Which components must be present on the device for it to function correctly?

A) Cas12-gRNA complex, DNA reporter, and microfluidic channel B) PCR thermocycler, primers, and gold electrode C) Isothermal incubator, Fab fragments, and antibody electrode D) Reverse transcriptase, spin coater, and SU-8 mold

A Cas12-gRNA complex, DNA reporter, and microfluidic channel

13 Which of the following best describes why microfluidics is preferred over traditional biopsy methods for cancer detection?

A) Microfluidics can sequence entire tumor genomes faster B) Microfluidic devices eliminate false positives entirely C) Traditional biopsies cannot detect circulating biomarkers D) Microfluidic cancer detection is less invasive than traditional methods

D Microfluidic cancer detection is less invasive than traditional methods

A clinician wants to use a single nanoparticle-based platform to both deliver chemotherapy and track tumor response in real time. Which technology is most appropriate?

A) Organ-on-a-chip with embedded biosensors B) Theranostic nanoparticles C) CRISPR-Cas12 diagnostic chip D) Antibody biosensor with gold electrode

B Theranostic nanoparticles

A protein-based biosensor is being designed for rapid antigen detection using bio-affinity interactions. Which of the following best describes its mechanism?

A) It uses PCR to amplify the target antigen signal B) It denatures the target protein before binding C) It exploits direct immunoassay interactions between the sensor and target molecule D) It requires isothermal amplification to generate a detectable signal

C It exploits direct immunoassay interactions between the sensor and target molecule

A researcher needs to fabricate microfluidic channels with nanoscale features that standard photolithography cannot achieve. Which fabrication method is most appropriate?

A) Hot embossing B) Fused deposition modeling C) Nanofabrication D) Wet etching

C Nanofabrication

A biosensor is being designed to detect a large nucleic acid analyte cheaply and reliably over long-term storage. Which biosensor type is most appropriate?

A) Enzyme biosensor B) Protein biosensor C) Nanozyme biosensor D) Nucleic acid biosensor

D Nucleic acid Biosensor

A fabrication team reports that their 3D printed microfluidic device cracks under compression during testing. Which fabrication method were they most likely using?

A) Fused deposition modeling B) Two photon polymerization C) Multi-jet printing D) Injection moulding

A Fused deposition modeling

You need a biosensor that is stable across varying pH and temperature conditions and can be manufactured cheaply at large scale. Which biosensor type best fits these requirements?

A) Enzyme biosensor B) Nucleic acid biosensor C) Nanozyme biosensor D) Protein biosensor

C Nanoenzyme biosensor

A lab requires straight, anisotropic channel profiles with precise control over etch depth. Which etching method should they use?

A) Wet etching with HF B) Dry etching C) Hot embossing D) Replica molding with SU-8

B Dry etching

A diagnostic company needs to mass produce microfluidic chips from thermoplastic materials at low cost and high accuracy. However, they are concerned about resolution limitations. Which fabrication method are they most likely using?

A) Injection molding B) Hot embossing C) Replica molding D) Two photon polymerization

A Injection molding

A researcher needs to detect a small molecular target using a biosensor. Which of the following biosensor types would be the LEAST suitable for this application?

A) Enzyme biosensor B) Nanozyme biosensor C) Nucleic acid biosensor D) Protein biosensor

D Protein biosensor

A lab wants to fabricate microfluidic devices from amorphous glass materials without using a cleanroom. Which fabrication method is most appropriate?

A) Replica molding with SU-8 B) Injection moulding C) Hot embossing D) Fused deposition modeling

C Hot embossing

A team needs the highest possible resolution among all 3D printing fabrication options for a complex microfluidic structure. Which method should they choose?

A) Fused deposition modeling B) Multi-jet printing C) Two photon polymerization D) Nanofabrication

C Two photon polymerization

A protein biosensor is being evaluated for detecting a small antigen target via direct immunoassay. A colleague suggests switching to a nucleic acid biosensor instead. Which of the following best justifies this switch?

A) Protein biosensors cannot perform direct immunoassay B) Nucleic acid biosensors are highly sensitive, selective, and ideal for long-range analytes with stable synthesis C) Protein biosensors require isothermal amplification D) Nucleic acid biosensors have higher specificity than protein biosensors for all target types

B Nucleic acid biosensors are highly sensitive, selective, and ideal for long-range analytes with stable synthesis

You are fabricating a microfluidic device for a biological detection system and require channel profiles with smooth, rounded edges to minimize cell damage during flow. Which fabrication method is most appropriate?

A) Dry etching B) Replica molding with SU-8 C) Fused deposition modeling D) Wet Etching

Wet etching

You are fabricating a mold for soft lithography that requires high resolution features, structural durability, and high aspect ratio channels. Which photoresist material is most appropriate for patterning the mold?

A) SU-8 B) LOR5C C) PMMA D) Polyurethane

A SU-8

A prototyping lab needs a simple, cost-effective 3D printing method compatible with a wide range of materials to quickly iterate microfluidic device designs. However, optical clarity of the channels is not a priority. Which fabrication method is most appropriate?

A) Two photon polymerization B) Multi-jet printing C) Hot embossing D) Fused deposition modeling

D Fused deposition modeling

A researcher needs a polymer for a microfluidic device that must return to its original shape after being deformed by external pressure, making it ideal for microvalves and micropumps. Which polymer class is most appropriate?

A) Thermoset B) Thermoplastic C) Elastomer D) Epoxy resin

C Elastomer

A lab wants to fabricate microfluidic channels using a polymer that can be remolded at elevated temperatures via hot embossing. Which polymer class is most suitable?

A) Thermoset B) Elastomer C) Siloxane D) Thermoplastic

D Thermoplatic

SU-8 is exposed to UV light and crosslinked during photolithography. Based on its polymer classification, which category does SU-8 belong to?

A) Thermoset B) Elastomer C) Thermoplastic D) Vinyl polymer

A Thermoset

A microfluidic device fabricated using a thiol-ene polymer begins showing nonspecific binding to target molecules during an assay. What is the most likely cause?

A) The polymer was not exposed to oxygen plasma B) Unreacted thiol groups are interacting with target molecules C) The polymer is not UV curable D) The device was not bonded to a glass slide

B Unreacted thiol groups are interacting with target molecules

A researcher needs a transparent, UV-curable polymer for a microfluidic device that can be made hydrophilic for aqueous sample flow. Which material is most appropriate?

A) PDMS B) PMMA C) Norland Optical Adhesive (NOA) D) Polyimide

C Norland Optical Adhesive (Tiol Ene)

You need to fabricate a microfluidic mold with an aspect ratio of 100:1 and resolution in the 50 nm range with smooth vertical sidewalls. Which mold fabrication method is most appropriate?

A) PMMA X-ray lithography B) SU-8 UV lithography C) Laser ablation D) Focused ion beam machining

A PMMA X-ray lithography

A team is designing a microfluidic device that requires both reversible and irreversible channel bonding options without complex processing steps. Which polymer is most appropriate?

A) PDMS B) SU-8 C) Polyurethane D) PMMA

C Polyurethane

Which of the following best explains why PDMS is widely used for cell culture microfluidic devices?

A) It is a thermoset with high glass transition temperature B) It is gas permeable, non-toxic, transparent, and can be surface-modified by oxygen plasma C) It has the highest aspect ratio of any polymer used in microfluidics D) It is a thermoplastic that can be remolded at elevated temperatures

B It is gas permeable, non-toxic, transparent, and can be surface-modified by oxygen plasma

A polymer is described as having a repeating —[R₂Si–O]— backbone with organic substituents at the silicon atom. Which polymer class does this describe?

A) Epoxy resin B) Polyurethane C) Thiol-ene D) Siloxane

D Siloxane

A fabrication engineer needs to pattern a mold on a curved surface. Standard photolithography is not working. Which approach should they use instead?

A) SU-8 UV lithography B) Hot embossing C) Direct writing using e-beam, ion beam, or laser D) Injection moulding

C Direct writing using e-beam, ion beam, or laser

Which of the following best explains why polymers are preferred over silicon for microfluidic device fabrication?

A) Polymers have higher electrical conductivity than silicon B) Polymers achieve higher aspect ratios than any silicon-based process C) Silicon cannot be used to fabricate molds for soft lithography D) Polymers offer lower material cost, a wide range of tunable properties, and easier process transfer from macro to micro scale

D Polymers offer lower material cost, a wide range of tunable properties, and easier process transfer from macro to micro scale

SU-8 is being used to fabricate a mold via UV lithography. Which of the following correctly describes a key property of this process?

A) SU-8 achieves aspect ratios of 100:1 and resolution in the 50 nm range B) SU-8 produces structures with aspect ratios around 40:1, smooth surfaces, and is compatible with cleanroom processes C) SU-8 requires X-ray lithography for adequate crosslinking D) SU-8 is a positive photoresist that dissolves upon UV exposure

B SU-8 produces structures with aspect ratios around 40:1, smooth surfaces, and is compatible with cleanroom processes

A researcher wants to separate particles in a microfluidic device without using any external energy source, relying solely on channel geometry. Which type of microfluidics is being used?

A) Active microfluidics using acoustic fields B) Passive microfluidics C) Active microfluidics using electric fields D) Optical field-based microfluidics

B Passive Microfluidics

A microfluidic device uses curved channels to generate secondary flows that improve liquid mixing. What is the name of this flow phenomenon?

A) Pinch flow fractionation B) Deterministic lateral displacement C) Dean vortices D) Dielectrophoresis

C Dean Vortices

You need to separate two populations of particles of different sizes at low Reynolds numbers using only geometric features in the channel. Which technique is most appropriate?

A) Acoustic field-driven mixing B) Pinch flow fractionation C) Micro filtration D) Deterministic lateral displacement

D Deterministic Lateral Displacement

A lab is designing a droplet microfluidic device that can detect specific DNA biomarkers. Which feature of droplet microfluidics enables this sensing capability?

A) Oil phases that amplify electrical signals B) Functional surfaces coated on the transduction area that sense unique biological structures C) Dean vortices that concentrate DNA into a single point D) Pulsed pressure fields that separate DNA by size

B Functional surfaces coated on the transduction area that sense unique biological structures

A microfluidic device needs to trap particles using both positive and negative forces without any mechanical components. Which technique is most appropriate?

A) Dielectrophoresis-based particle trapping B) Pinch flow fractionation C) Micro filtration D) Thermal field manipulation

A Dielectrophoresis-based particle trapping

An engineer needs to mix two liquids momentarily using pressure fields generated by an oscillating unit controlled by switching frequencies. Which active microfluidic technique is being described?

A) Acoustic field-driven micromixer B) Pulsed field-effect micromixer C) Inertial micromixer D) Optical field-based transducer

B Pulsed field effect micromixer

A researcher wants to separate particles based on their dielectric properties using an electric field in a microfluidic device. Which active microfluidic approach is most appropriate?

A) Magnetic field separation B) Thermal field manipulation C) Electric field-based separation D) Optical field manipulation

C Electric field-based separation

A microfluidic chip needs to rapidly heat particles to induce a reaction and then return to normal operating temperature for continued use. Which active microfluidic field is being used?

A) Acoustic pressure field B) Optical field C) Magnetic field D) Thermal field

D Thermal Fields

A lab wants to focus nanoscale biomolecules into a straight line within a microchannel using light. Which technique is most appropriate?

A) Optical field-based transducers B) Dielectrophoresis C) Acoustic standing waves D) Pulsed field-effect mixing

A Optical field-based transducers

A microfluidic device uses a membrane-like structure to capture larger particles while allowing smaller ones to pass through. Which technique is being used, and what is a key concern with this approach?

A) Deterministic lateral displacement — low capture efficiency B) Micro filtration — clogging must be mitigated C) Pinch flow fractionation — limited to low Reynolds numbers D) Particle trapping — requires magnetic particle labeling

Micro filtration — clogging must be mitigated

A researcher notices that water does not wet the surface of their PDMS microfluidic channel, causing poor fluid flow. What is the most likely cause and the correct solution?

A) The PDMS was over-cured — increase mixing ratio B) CH3 groups make the surface hydrophobic — apply O2 plasma treatment to make it hydrophilic C) The PDMS was bonded incorrectly — re-bond using pressure alone D) The channel aspect ratio is too high — reduce channel depth

B CH3 groups make the surface hydrophobic — apply O2 plasma treatment to make it hydrophilic

A microfluidic device requires optical detection using fluorescence and Raman spectroscopy. Which material property is absolutely required for the device substrate?

A) Optical transparency at the detection frequencies of interest B) Ionic bonding structure C) High electrical conductivity D) Hydrophobic surface chemistry

A Optical transparency at the detection frequencies of interest

A PDMS stamp with very high aspect ratio features is being used for micro-contact printing. The team notices replication errors in the transferred pattern. What is the most likely cause?

A) The SAM resist was applied incorrectly B) The stamp deformed due to pairing or sagging at extreme aspect ratios C) The PDMS was not treated with O2 plasma before stamping D) The substrate was etched with RIE before wet etching

B The stamp deformed due to pairing or sagging at extreme aspect ratios

In micro-contact printing (μCP), after the PDMS stamp transfers the SAM resist to the substrate, what is the next step if the structural layer needs to be etched?

A) Direct RIE of the structural layer B) Injection of polymer precursor into the relief areas C) O2 plasma treatment followed by bonding D) Wet etching to remove the sacrificial layer prior to RIE

D Wet etching to remove the sacrificial layer prior to RIE

A polymer used in a microfluidic electrophoresis device begins to fail under the applied electric field and overheats. Which machinability requirement was not met?

A) The polymer must not absorb at detection frequencies B) The polymer must be optically transparent for UV-Visible detection C) The material must withstand electrical fields and be able to dissipate heat D) The cover plate must withstand bonding temperatures

C The material must withstand electrical fields and be able to dissipate heat

Which of the following correctly distinguishes free radical photopolymerization from cationic photopolymerization in the context of soft fabrication?

A) Free radical is associated with acrylates; cationic is associated with epoxies like SU-8 B) Free radical is associated with epoxies; cationic is associated with acrylates C) Both free radical and cationic polymerization are initiated by thermal energy only D) Cationic polymerization requires UV wavelengths above 600 nm

A Free radical is associated with acrylates; cationic is associated with epoxies like SU-8

A researcher needs to fabricate microstructures in the micro and nano regime using hot embossing. Which mold material is required for this application?

A) PDMS and glass B) Epoxy resin and aluminum C) PMMA and polyurethane D) Silicon and Nickel

D Silicon and Nickel

biomaterial is being selected to serve as an anchor for binding biomolecules of interest in a microfluidic assay. Which class of biomaterial function does this represent?

A) In vivo — implanted in living tissue B) In vitro — transport or containment function C) Process function — functionalized material D) Elastomeric function — deformation and recovery

C Process function — functionalized material

Silicon and glass microfluidic substrates are strong and brittle. Which type of atomic bonding is responsible for these mechanical properties?

A) Covalent bonding — sharing of electrons B) Metallic bonding — losing of electrons C) Ionic bonding — gaining of electrons, found in ceramic materials like silicon and glass D) Hydrogen bonding — partial charge interactions

C Ionic bonding — gaining of electrons, found in ceramic materials like silicon and glass

A lab needs to fabricate a complex 3D microfluidic prototype rapidly without a photomask, building it layer by layer from a computer rendering. Which fabrication method is most appropriate?

A) Microtransfer molding B) Hot embossing with a nickel mold C) Micro-contact printing with a PDMS stamp D) Stereolithography

D Stereolithography

A researcher is designing a brain-on-a-chip model to study seizure activity. Which of the following correctly describes how seizures are induced and detected in this device?

A) Free fatty acids are added to trigger lipid formation, detected by fluorescence B) Acoustic standing waves are used to detect abnormal neural firing patterns C) Two bone cell cultures are separated by channels to detect electrochemical signals D) A microelectrode array detects seizure-like activity and kainic acid is added to induce seizures

D, A microelectrode array detects seizure-like activity and kainic acid is added to induce seizures

A microfluidic device is being used for a liver-on-a-chip study of obesity. Which of the following correctly describes the mechanism used in this device?

A) Kainic acid is added to induce metabolic stress in hepatocytes B) Free fatty acids are used to trigger lipid formation in adipose tissue cells C) Two channels separate endosteal and perivascular cell cultures D) Gut microbiome signaling is replicated using multiple cell culture channels

B Free fatty acids are used to trigger lipid formation in adipose tissue cells

During microtransfer molding (μTM), how does the process differ from micro-contact printing (μCP) in terms of where the material is placed?

A) In μTM the material is on the raised areas of the stamp, in μCP it is in the relief areas B) Both μTM and μCP place material identically but differ in curing temperature C)In μTM the material fills the relief areas of the mold, in μCP the material is on the raised areas D) μTM uses SAM resist while μCP uses a liquid polymer precursor

C In μTM the material fills the relief areas of the mold, in μCP the material is on the raised areas

A microfluidic channel is being filled using micromolding in capillaries (MMIC). Which driving force fills the channels with polymer solution in this process?

A) Capillary action B) Pressurized injection through a sprue C) O2 plasma treatment drawing fluid into channels D) Acoustic pressure waves driving fluid flow

A Capillary action

A polymer device is being fabricated using the variotherm process. Which of the following correctly describes the sequence of steps?

A) Polymer is melted, injected under pressure, cooled, then reheated for demolding B) PDMS is cast over a silicon wafer master, cured, and peeled off C) Thermoplastic is compressed between two mold inserts, softened by heating, then formed by compression D) Mold is evacuated and heated above the glass transition temperature, molten polymer is injected under pressure, then cooled prior to demolding

D Mold is evacuated and heated above the glass transition temperature, molten polymer is injected under pressure, then cooled prior to demolding

A researcher needs to fabricate a microfluidic device from a bone-on-a-chip model that requires cell-to-cell signaling between two distinct bone cell populations. Which of the following correctly describes the design?

A) A single channel containing both endosteal and perivascular cells mixed together B) Two cultures of endosteal and perivascular bone cells separated by two channels allowing cell-to-cell signaling C) Free fatty acids are introduced into a single culture to differentiate bone cell types D) A microelectrode array separates the two bone cell populations by electrical stimulation

B Two cultures of endosteal and perivascular bone cells separated by two channels allowing cell-to-cell signaling

A contact angle of 120° is measured on a microfluidic device surface. What does this indicate about the surface and how will it affect aqueous sample flow?

A) The surface is hydrophilic and water will wet it easily B) The surface is hydrophilic and represents complete wetting C) The surface is hydrophobic and water will not adhere to it, impeding aqueous flow D) The contact angle indicates covalent bonding between water and the surface

C The surface is hydrophobic and water will not adhere to it, impeding aqueous flow

A researcher is using photopolymerization to cure an epoxy-based material for a microfluidic mold. Which polymerization mechanism is occurring and what is its defining characteristic?

A) Free radical polymerization — initiated by unpaired electrons from UV-exposed photoinitiators B) Thermal polymerization — heat drives crosslinking of epoxide groups without UV C) Ionic polymerization — involves metallic bonding and electron loss at the active site D) Cationic polymerization — the active site carries a positive charge and monomers are added until termination

D Cationic polymerization — the active site carries a positive charge and monomers are added until termination

A microfluidic device polymer absorbs strongly at 280 nm. A researcher wants to use fluorescence detection at this wavelength. Why is this a problem and what does the lecture say is required?

A) Absorption at 280 nm will cause the polymer to become hydrophobic, blocking fluid flow B) The polymer must not absorb at the detection frequencies of interest — absorption will interfere with fluorescent detection C) Absorption causes ionic bonding between the polymer and the fluorescent dye D) The polymer will undergo free radical polymerization when exposed to detection wavelengths

B The polymer must not absorb at the detection frequencies of interest — absorption will interfere with fluorescent detection

A lab is choosing between stereolithography (SL) and microstereolithography (MSL) for fabricating a microfluidic device. Which of the following best describes the key advantage of MSL over SL?

A) A MSL offers submicron resolution with finely focused UV laser spots and layers 1-10 mm thick, compared to the lower resolution of standard SL B) MSL uses a computer rendering while SL requires a physical photomask for every layer C) MSL is faster because it does not require a z-axis translational stage D) MSL uses cationic polymerization while SL uses free radical polymerization

A MSL offers submicron resolution with finely focused UV laser spots and layers 1-10 mm thick, compared to the lower resolution of standard SL