A biochip for recording electrophysiological signals of nematodes

Group 13-27Advisor: Liang DongGroup members:Xuan QiaoYuncong Chen Yang CuiRuiyu Chen

IntroductionOverviewProject designRelated backgroundProject working process

Overview of our project

General view

Detail structure

Amplifier circuit Testing environment

Concept sketchBiochip device: container as an

environment

Electrodes: electrophysiological signal transform

Amplifier: electrophysiological signal measurement

Testing TargetC. Elegans

Our DesignHigh efficient trappingConvenient electrodes

Our Design30 um gold electrodes 15 um channels

Why C. elegansThe genes of C. elegans nematodes

are similar to those of human beings.

Nematodes are simple, easy to study

Biologists use C. elegans as model system to study toxicology and discover new drugs for human metabolic and degenerative diseases

Why Electrophysiological signals Electrophysiological signals from

C. elegans provide information about the activity of the pharynx (throat) which pumps like a heart during feeding

C. elegans has a distinct set of drug receptors present on its pharynx.

Why biochipLow cost- $30/liter can make a hundred of our devices

High throughput- Once you have the design, it is easy to make hundreds of biochip devices

Simple operation- Biochip devices are easy to use

SchameticAmplifier Design

SimulationResult:

Testing inveriment1.We don’t have the

optical table to eliminate the influence from movement of people

2. When we do the test in Coover, there is no wire box to enclose the testing area to filter the noise in the air

Testing result

2 pA

1000 m s

2 pA

50 m s

The amplitude shows how strong the nematode is pumping.

The frequency shows how frequent the nematode is pumping.

Initial Contraction

Terminal Contraction

Working process

Pick worm Spin the Biochip

Worms in the bio chip

By using the spinning coder, the biochip can get the worms in every channels. This is why we call it “high trapping rate”

Working process

ChannelNematode Electrod

ePharynx

Working process

Challenges in The Project• 15 um channel fabrication

• Gold etching process

• No alignment mark

• Noise reduction

Questions

Back up slides

Constraints & ConsiderationsAll equipment and device need to set up on a experiment table.

Group members should wear lab cloth, gloves and goggles.

Gold etching with strong acid

Our project

Non-functional requirementsdevice fabricationTaking Picture of Worms and

Taking video

Electrodes fabricationDo alignment with microscope

Division of LaborXuan & Yuncong & Yang: device

design, fabrication and Electrodes fabrication

Abhishek & Ruiyu: amplifier design and construction

Potential RisksAlignment for device and

electrodesChemicals, sharps, UV exposure,

wormsBurning of op-amps, resistors,

capacitorsNoisy signalStrong acid in electrodes

fabricationWorms die in culture

MitigationBeing generally diligent will go a

long wayDuctility: most experienced

member will make device to ensure proper thickness

Safety risks: all trained in lab safety, know proper procedures to avoid accidents

Burned components/noisy signal: use of quality components and careful construction

Market Surveytraditional experiment: 1. trap and test worms one by one2. Expensive and waste time

Our design: 1. trap and test 16 worms at the same time 2. The device is small and cheap