# Ultrasonic transducer selection

## 1 Considerations for the choice of frequency, power, probe size

### 1.1 Frequency
There are large frequency range available in market like 20,25,40kHz, we chosen 20kHz for our experiment, bubble size depend on ultrasonic frequency with increasing ultrasonic frequency bubble size keep decreasing.
- Reason for choosing lower frequency ultrasonic transducer is beacause lower frequency produce larger cavitation bubble which result of each implosion of a cavitation bubble having a higher energy level. As frequency increase size of the cavitation bubble become smaller which means that each bubble implosion is will relative less energy
### 1.2 Power
- Increasing the ultrasonic power results in a larger number of cavitaion bubble being produced as the size of bubble depends on frequency and quantity of bubble( buuble density)depends on ultrasonic power.
- At lower energy only most favourable site grow into cavitation bubbles. as power increase, there is sufficient cause the less seed site to grow into cavitation bubbles and overall number of bubble increase.
- Amplitude is depend on input power, incresing amplitude increase bubble volume cloud, thickness of bubble layer grew with increase amplitude.
<cite>[K.L. Tan(2019) et al.][2]</cite>

#### 1.2.1 Calculations and literature survey for power selection

##### 1.2.1.1 Conversion from device wattage to acoustic power transmitted to fluid
- for caloremetric measurement , ultrasound switch on for 15 minutes, average value of acoustic power for electrical power input is given in figure, this graph demonstrate the approxx. 80% of electric power input is converted into ultrasonic energy.
- energy transfer is higher at elevated pressure as compared to ambient pressure this might be because hydrolic pressure might enhanced energy coupling of ultrasonic horn with and liquid
<cite>[Maikel M. van lersel(2008) et al.][1]</cite>

##### 1.2.1.2 Correlation between acoustic cavitation and transmitted acoustic power
$$ P_o=\sqrt{\frac{2\rho C P_{in}}{A_s}}$$
$$ P_o= Acoustic\ Pressure $$
$$\rho= Density\ of\ fluid$$
$$C= Velocity\ of\ sound\ in\ liquid$$
$$ A_s= Surface\ area$$
$$ P_{in}= Acoustic\ power( Acoustic\ energy)$$

### 1.3 Probe size
Standard probe size is available is 12mm, we order 8mm probe size diameter.

## 2 Vendor selection criteria

- Est. price
<i class="fa fa-table"></i>

|Company | Price | Frequency| Electrical power(watt)|available probe diameter(mm)|
| -------- | -------- | -------- |--------|----|
Auto ultrasonic|300000|20kHz|250, 500, 750, 1000, 1500, 2000|6,10,12,15,20
Johnson plastosonic|141600|20kHz|750|12
Sonics|500000|20kHz|750|13,19,25
Lab man|152000|20-25kHz|650|2,3,6,8,10,12
Pci analytics|208000|20kHz|250, 500, 750, 900, 1200, 1500, 1800|8, 10, 12, 15, 18, 20
Dolphin|360000|20Khz|250,500|6,9.5
Hielscher Ultrasonic Technology|1000000|20kHz|400|--
Q sonica|600000|20kHz|700|13,19,25
- Flanged/unflanged probe
Only two company provide flange type probe sonicator
2.1 Auto ultrasonic
2.2 Johnson plastosonics
- Compatibility with existing generators at IITK
Only autoultrasonic provide Probe, booster and convertor which is compatible to Existing generator(prof. Arvind Kumar)

## 3 Preliminary experiments for selecting 750W/1000W generator

### 3.1 Bubble generation at elevated pressures (40 bar) without flow

- Optically accessible cell which can sustain 40 bar.

### Nitrogen cylinder and accessories
- Abhigyan traders provide nitrogen cylinder with gas @ 16500
- Nitrogen pipeline
Pipeline work is almost finised

## 4 Other considerations for purchase decision

- Time and cost estimates for probe (separate), generator (separate), and complete set
- Separate probe is not useful for us,we need to buy convertor, booster, and probe together that cost is around 100000, and generator price is 200000, they have uploaded(17 dec) on gem portal to get L1 and waiting for approval till now(21 dec).
- We initiated the purchase so we are waiting for GeM portal approval, there was another option to buy probe, convertor and booster combined cost was around 100000, probe cost was around 25000, convertor cost was around 50000 and booster cast was around 25000, if there will be any possibility we can go with 25000 each and 4 time payment
- Complete set cost is around 300000 that we are going in one go
## Relationship of Amplitude and Wattage
* Sonication power is measured in watts. Amplitude is a measurement of the excursion of the tip of the probe (probe is also known as a horn).
* Some ultrasonic processors have a wattage display. During operation, the wattage displayed is the energy required to drive the radiating face of a probe, at that specific amplitude setting against a specific load, at that particular moment. For example, the unit experiences a higher load when processing viscous samples then when compared to aqueous samples.
* The ultrasonic processor was designed to deliver constant amplitude, to your liquid sample, regardless of these changes in load,As the resistance to the movement of the probe increases (increased load on the probe)The displayed wattage readings will vary as the load changes, however the amplitude will remain the same.
* The resistance to the movement of the probe determines how much power will be delivered to maintain amplitude. For example, a ½” probe at 100% amplitude will require approximately 5 watts to operate in air. The amplitude of this probe is approximately 120um. Insert the probe in water and the wattage reading will increase to approximately 90 watts. The wattage required to operate the probe will increase as the load increases but the amplitude remains the same.
## Power vs. intensity
* Power is the measure of the electrical energy that is being delivered to the convertor. It is measured in watts and displayed on the sonicator’s screen. At the convertor, the electrical energy is transformed into mechanical energy. It does this by exciting the piezoelectric crystals causing them to move in the longitudinal direction within the convertor. This change from electrical into mechanical energy causes a motion that travels through the horn/probe causing the tip to move up and down.
* The distance of one movement up and down is called its amplitude. The amplitude is adjustable.Each probe has a maximum amplitude value.
* Amplitude and intensity have a direct relationship. If you operate at a low amplitude setting, you will deliver low intensity sonication. If you operate at a high amplitude setting, you will have high intensity sonication. In order to be able to reproduce results, the amplitude setting, temperature, viscosity and volume of the sample are all parameters that need to remain consistent. The amplitude, not the power, is most critical when trying to reproduce sonication results.
* Power has a variable relationship with amplitude/intensity.
* . While sonicating both samples at the same amplitude setting the power/wattage will differ because the viscous sample will require more watts in order to drive the horn. The viscous sample puts a heavier load on the probe so they system must work harder to vibrate up and down at the same amplitude setting
<cite>[Sonicator
ULTRASONIC PROCESSOR
Part No. Q500
OPERATION MANUAL][3]</cite>

[1]:https://www.sciencedirect.com/science/article/pii/S135041770700154X
[2]:https://www.sciencedirect.com/science/article/pii/S1350417719303748
[3]:https://lab.vanderbilt.edu/wp-content/uploads/sites/21/public_files/q500_manual_rev_3-12.pdf

# Our selected sonicator specifications

1. * Power input variation through sonicator generator with 250,500,750 and 1000 watt at 20kHz frequency( Basically by varying the power input to the generator, we are directly changing the probe tip vibration at the mean position at respective amplitude are 105,120,135 and 150 micrometer) It is expected that number of bubble generated below the probe sonicator will be increase with amplitude, area of bubble cloud increase.