user7324: I like to build a fluid(liquid) level detector using Arduino that can send 2 types of information:

Status of the Fluid Container (Empty,Full or Below Required Level)
Location of Fluid Container

Now I like to know how small and compact such a fluid detector can be so that it can be placed in vessels, containers, tanks, etc. without causing any contamination to the fluid.
In addition, how can I interface this fluid detector with external systems like a smartphone app or cloud based app, etc. 
What Arduino would i be using for the said purpose and why?

user19300: Your question should be broken into a minimum of two parts. 
The first, regarding the sensor, can be addressed with at least one specific product, although there may be others of this nature. It is a teflon coated pressure sensitive strip placed into the holding container or tank. Teflon is a non-reactive plastic and will not contaminate the substance in the tank, unless you are measuring extraordinarily reactive chemical liquids. One example is 
Chemical eTape which is available in lengths from 130mm to 800mm.
 
This particular product is offered in three different interface types, all of which are acceptable to a properly configured Arduino.
The second portion of your question regarding the smartphone and type of Arduino is going to depend on how you plan to use the data you'll collect with the sensor. This aspect of the question is also extremely broad, as there are many solutions, including Blynk, SMS, WiFi and others.
You will want to "start small," and create a local Arduino-only interface, to ensure that you can properly code the sensor to present the results you require.
Once you have the data, you would then explore the many options available for distribution and dissemination. 

7324: <p>I like to build a fluid(liquid) level detector using Arduino that can send 2 types of information:</p>

<ol>
<li><p>Status of the Fluid Container (Empty,Full or Below Required Level)</p></li>
<li><p>Location of Fluid Container</p></li>
</ol>

<p>Now I like to know how small and compact such a fluid detector can be so that it can be placed in vessels, containers, tanks, etc. without causing any contamination to the fluid.
In addition, how can I interface this fluid detector with external systems like a smartphone app or cloud based app, etc. </p>

<p>What Arduino would i be using for the said purpose and why?</p>
 19300: <p>Your question should be broken into a minimum of two parts. </p>

<p>The first, regarding the sensor, can be addressed with at least one specific product, although there may be others of this nature. It is a teflon coated pressure sensitive strip placed into the holding container or tank. Teflon is a non-reactive plastic and will not contaminate the substance in the tank, unless you are measuring extraordinarily reactive chemical liquids. One example is 
<a href="http://milonetech.com/products/chemical-etape-assembly" rel="nofollow noreferrer">Chemical eTape</a> which is available in lengths from 130mm to 800mm.</p>

<p><a href="https://i.stack.imgur.com/32L74.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/32L74.jpg" alt="enter image description here"></a> </p>

<p>This particular product is offered in three different interface types, all of which are acceptable to a properly configured Arduino.</p>

<p>The second portion of your question regarding the smartphone and type of Arduino is going to depend on how you plan to use the data you'll collect with the sensor. This aspect of the question is also extremely broad, as there are many solutions, including Blynk, SMS, WiFi and others.</p>

<p>You will want to "start small," and create a local Arduino-only interface, to ensure that you can properly code the sensor to present the results you require.</p>

<p>Once you have the data, you would then explore the many options available for distribution and dissemination. </p>
