Team:SUSTech Shenzhen/Hardware
Hardware
Model
Contents
Introduction
We are aiming to evolve a more sensitive mechanical sensitive channel (MS channel). When MS channels are stimulated by mechanical force, a Ca2+ influx is triggered. To measure the performance of MS channel, we chose sound to produce mechanical force and GECO protein as Ca2+ indicator to reflect the channel sensitivity through its fluorescence change.
Sound part
In this part, we aim to explore the effect different frequency on cell. Frequencies from 300Hz to 1.7MHz were tried to observe whether the cell with MS channel can response differently to different frequency. If so, frequency orthogonal audiogenetic parts are hopefully to be developed. Meanwhile, the equipment was also designed to be easy to change sonic power, in order to choose the most suitable intensity being harmless to cell.
Sonic Stimulation
Signal generation
A dual channel function/arbitrary waveform generator (Feel Tech FY2303) was used to generate sound wave signals. It can generate 1uHz to 2MHz, 0v to 20v signals. An amplifier was used to amplify the wave signal output by the wave generator.
Sound generator
Buzzer
Buzzer is a thin metal plate attached with a piezoelectric ceramic. When varying voltage is added to its two ends, it deforms coordinately. Whereas, its low and high frequency response is weak, and can only be used to generate sound under 15 KHz. For cell safety, we fix it on the bottom of cell dish for cell stimulation.
Speaker
As the low and high frequency response of buzzer is weak, speaker (Type: rsiym) was chose for complementation. Its power can reach 3W and it was drenched in culture medium for low frequency experiment.
Balanced Amateur
Buzzers and speakers both have short comes. For buzzers, sound could mainly be absorbed by cell dish bottom and the power was very weak. Speaker is more powerful though, it is cell toxic and not stable. For more, they both generate a vertical pressure to cell but not shear force. So, we promoted a third plan using balanced amateur.
Balanced amateur is very stable and small. A steel tube was fixed on it to drench in to water. Thus it can generate a shear force horizontal to cell dish， which is closer to the mechanism of human hearing. The problem is that its power is not strong enough to trigger a cell response.
Lab Circuit
The following is a brief circuit of sound generator circuit.
ultra sound stimulation
Seeing cell response increased with stimulating frequency, and hearable sound can hardly trigger strong cell response. Ultrasound was come up with. There were 4 kinds of ultrasound devices constructed.
Horn-shaped ultrasound generator
We first constructed this device using circuits from ultrasound cleaner. However it was easy to destroy the circuit due to too small load.
Piezoelectric Energy Transducer.
A new ultrasound device was designed seeing the horn-shaped device is too powerful and unstable. Piezoelectric energy transducer was chose for a much slighter stimulation.
Ultrasound signal generator:
KINGCHIP SD02-JSQ-V2.4 circuit, 5V DC input. 1.7MHz output.
Power control:
The signal output from KINGCHIP SD02-JSQ-V2.4 circuit was input to the following conrol circuit designed by ourselves. Output power can be controled by changing resistance. Microproccsor Arduino UNO was rogrammed to control stimulation time pattern.
Energy Transducer:
1. 1MHz energy transducer used in fog generator was used to generate stable ultrasound. Cell toxity experiment show that it has little and tolerable cell toxity.
2. For quantified stimulation, a calibrated ultrasound energy transducer was used.
Data
Diameter: 8.5mm
Thinness: 22mm
For 23Vp-p 1MHz input, 1.9W/cm2 (3mm for from head)
Lab Circuit
Device I
Two 1MHz low power ultrasound stimulators are implemented for program controlled exeriment.
Device II
One 1MHz ultrasound stimulator was implemented with larger size and maximun power. Control part and electric part were seperated into two layers for safety.
1. Stimulation program loading.
2. Fix stimulator in proper position.
3. Turn on the switch and change resistance for proper ultrasound intensity.
4. Start stimulation experimrnt.
