We need sensors to monitor temperature of the fluids and the lung chamber, flow rate of both the trachea and blood vessel fluids and air flow rate through trachea, and pH levels in order to confirm that nothing has been contaminated and to note at what point the lung has properly been rinsed of the SDS decullarizing detergent.
In addition to information below, Joe Ross from PAR Associates LLC has advised that both temperature and flow rate of LIQUIDS can be measured using infrared sensors outside the tubing. The tubing would need to be a completely clear tubing for this to work. For an accurate quote and detailed information he wants us to send him a sample of the tubing and some information in the fluids in use.
IR will NOT work for our purposes.
We would like these sensors to connect to a data acquisition system so that all data can be read on the same central PC that controls the pump.
The following is a link for a Data Acquisition Starter Kit: http://www.dataq.com/products/startkit/di145.html.
In addition, the following page gives information on how to properly hook up something with a 4-20 mA output (see pH below): http://www.dataq.com/applicat/articles/process_current1.htm.
The above page instructs to use a resistor to convert the current to a properly corresponding voltage. However, using this method would convert the 4mA to 1V, rather than to 0. This Nerd Blog gives instructions on how to better convert the 4 to 20 mA to 0 to 5/10 V.
One of the easiest solutions seems to be to use a RCV420 Chip. This chip costs only a few dollars each and converts any 4 to 20 mA input and gives a 0 to 5 V output.
Here are several data sheets for the RCV420: http://focus.ti.com/lit/ds/symlink/rcv420.pdf; http://focus.ti.com/lit/an/sbva003/sbva003.pdf; http://focus.ti.com/lit/an/szza045/szza045.pdf.
The following page provides more information on DAQ, including a link to signal conditioning, which explains how to turn different signals into something readable: http://sine.ni.com/np/app/main/p/ap/daq/lang/en/pg/1/sn/n17:daq/fmid/652.
The data acquisition board that we currently plan on using is the NI 6211.
Jose from Cole Parmer has advised that each flow meter can only measure flow in one direction and to measure any 2-way flow we would need 2 oppositely facing sensors. He did, however, guarantee that if media were to flow the wrong way it would not damage the sensor, but would simply not give an accurate reading.
The Omega representative said that flow the opposite would still give a reading; however, it would not give a negative number to indicate that the flow had been reversed. HOWEVER, the user manual of the products indicates that the sensor would NOT function if there were an opposite flow.
To measure flow through the 'trachea tubings' we would need to be able to measure flows close to 400 mL/cycle (each side of the lung taking in half of the 800 mL total).
In order to measure flow through the pulmonary artery/vein we would need to measure total flows between 4-8 L per minute.
Some of these sensors would need to be connected to a 'threading to tubing' adapter. See Tubes and Valves
The following page has details for FLR1013 & FLR1013-D: http://www.omega.com/ppt/pptsc.asp?ref=FLR1000&Nav=greb07
These parts can detect the fluid flow rates that would be passing through the 'trachea' - 1- 10 L/min.
The -D model is more expensive and has a built in display, while the other model is cheaper, but would have to be attached to some sort of data acquisition system.
This sensor would require power from the data acquisition system of 12.5 Vdc and would give an output signal to the DAQ of 0 to 5 Vdc.
These models are not autoclave-able.
The following sensor is autoclave-able and for fluids only: http://www.omega.com/toc_asp/frameset.html?book=Green&file=FTB9500&flag=1.
This sensor is more expensive than the others and would still require additional conditioners to linearize the output and to convert the output to either 4-20 mA or to 0-5 V.
DISCONTINUED
The following sensor is autoclave-able if we gte the high temperature option: Omega Model: FTB1411-HT
This will read flow rates of 2.3 to 11.3 L/min
It has connections on both ends of 1/2” threaded connection
And if connected to Omega Model: DPF701-A we will get either a 4-20 mA or 0-10 V output.
The following is a set of equipment that Cole Parmer offers to properly record our liquid flow. This option appears to be more expensive and requires several adapters and connections.
Flow meter/transmitter: http://www.coleparmer.com/catalog/product_view.asp?sku=3271852
Tubing to connect to compression fittings: http://www.coleparmer.com/catalog/product_view.asp?sku=9550106&pfx=EW
Compression to threading adapter: http://www.coleparmer.com/catalog/product_view.asp?sku=0638450&pfx=EW
Threading to 3/8” barbed connection: http://www.coleparmer.com/catalog/product_view.asp?sku=3061042&pfx=EW
Both of these options do not appear to have an appropriate output.
Flow sensor for ~.75-~15 L/min: http://www.gemssensors.com/Products/Flow/Electronic-Flow-Sensors/Turbo-Flow/~/media/GemsNA/CatalogPages/FT330.ashx
Flow sensor for .5-30 L/min: http://www.gemssensors.com/Products/Flow/Electronic-Flow-Sensors/Turbo-Flow/~/media/GemsNA/CatalogPages/ft-110-series-cat.ashx
For the models below that are not autoclave-able or sterilize-able, Cole Parmer recommended using a sterilizing filter after the flow meter so as to essentially make it irrelevant whether the flow meter itself is autoclave-able: CP Model #: 02909-60 is smaller and has smaller pores; CP Model #: 02909-55 is larger with larger pores, but will fit our tubing better.
According to a rep from Omega there are no gas flow meters that are autoclave-able.
According to a rep from McMflow there are no gas flow meters that are autoclave-able.
The following page has details for FLR1201 & FLR1201-D AND FLR1202 & FLR1202-D: http://www.omega.com/ppt/pptsc.asp?ref=FLR1000&Nav=greb07
These parts can detect the air flow rates that would be passing through the 'trachea' - 2- 10 L/min AND 4 -20 L/min respectively.
The -D model is more expensive and has a built in display, while the other model is cheaper, but would have to be attached to some sort of data acquisition system.
This sensor would require power from the data acquisition system of 12.5 Vdc and would give an output signal to the DAQ of 0 to 5 Vdc.
In addition, the 1201 connects to a 1/4” acetal tube fitting - not 3/8”; however this may not matter. The 1202 connects to 3/8”.
These models are not autoclave-able.
The following is a set of equipment that Cole Parmer offers to properly record our gas flow. This option appears to be more expensive and requires several adapters and connections.
Option 1 - meter/transmitter - cheaper, aluminum; however, Jose recommends steel as more compatible and durable: http://www.coleparmer.com/catalog/product_view.asp?sku=3265809&pfx=EW
Option 2 - meter/transmitter - more expensive steel: http://www.coleparmer.com/catalog/product_view.asp?sku=3265829&pfx=EW
Tubing to connect to compression fitting: http://www.coleparmer.com/catalog/product_view.asp?sku=9550100&pfx=EW
Compression to threading adapter: http://www.coleparmer.com/catalog/product_view.asp?sku=0638420&pfx=EW
Threading to 3/8” barbed connection: http://www.coleparmer.com/catalog/product_view.asp?sku=3061039&pfx=EW
This is not autoclave-able.
The following link is to a gas flow meter that will work with our flow rates and will give an analog output: http://www.mcmflow.com/displayproduct.asp?PRODUCT=100.
Waiting to hear back if it is autoclave-able.
The Cole Parmer catalog starting on p 1333 contains a list of pH sensors with threaded ends to allow it to be inserted in-line (using a T-fitting to our tubing. These pH electrodes would need to be connected to something that could read from the sensor and then transmit.
Jim from Cole Parmer recommended the following transmitter, which would transmit both temperature and pH readings with a 4 to 20 mA output: http://www.coleparmer.com/catalog/product_view.asp?sku=5671720&pfx=EW
He recommended using a pH electrode that lists having a 100 ohm RTD ATC element and has tinned ends. In addition, some of these electrodes have “flat surfaces,” which apparently keep the glass electrode safer. One of the cheaper electrodes that fit this description is http://www.coleparmer.com/catalog/product_view.asp?sku=2700312&pfx=EW.
In addition, Jim said that we would need the following $12 adapter: http://www.coleparmer.com/catalog/product_view.asp?sku=5610560&pfx=EW.
Jose confirmed that this arrangement would work and gave the following information regarding adapter pieces needed to use the system in-line:
This would be used to place the pH sensor in-line using 3/4” NPT connections: http://www.coleparmer.com/catalog/product_view.asp?sku=2700380&pfx=EW
This would convert the 3/4” NPT connections to our 3/8” barbed connections: http://www.coleparmer.com/catalog/product_view.asp?sku=3061049&pfx=EW
The following is a link to a fully submersible pH electrode (that would need to be connected as with the previous sensor): http://www.coleparmer.com/catalog/product_view.asp?sku=3580523&pfx=EW.
Jose confirmed as well that this electrode would be compatible with the same transmitter as above and would need the same $12 adapter.
Infrared sensors can only work with fluid that it will not see through, and will therefore not work with gas/air/
There are several types of standard temperature probes including Thermocouple probes, RTD probes, and Thermistor probes.
The thermocouple probes work based on the fact that an electromagnetic force is produced when heat is applied to a junction between 2 different metals. This emf is compared to that of a reference point on the wires.1)
RTD probes work based on the fact that the resistance of the metal probe increases as the temperature increases.2)
The thermistor probes have a thermally active resistor composed of metal oxides encapsulated in glass.3)
All the above sensors have large temperature ranges that encompass our 37 C mandatory temperature.
The following is a table that compares the advantages of each type of sensor.((Cole Parmer 2011-2012 Catalog. P 2086)
| Feature | Thermocouple | Platinum RTD | Thermistor |
|---|---|---|---|
| Accuracy | Low | Medium | High |
| Repeatability | Low | High | Medium |
| Long-term Stability | Low | High | Medium |
| Linearity | Average | Good | Poor |
| Time Response | 2 to 5 sec | 2 to 5 sec | 1 to 2 sec |
Given the above information the RTD probes seem to be a better option than the other two as they have the highest long-term stability and the highest repeatability and the best linearity (which should help the DAQ read it better). In addition, it still does have decent accuracy. The second best choice may be the thermistor, depending on how bad it is that they have a very poor linear relationship between voltage output and temperature.
The following is a link to an RTD temperature probe that has a maximum error of .4 F and has a range of 0 to 400 F: http://www.coleparmer.com/catalog/product_view.asp?sku=3288400&pfx=EW.
Jose said that the above model has a 1/4” threaded end, which would make it easier to use in-line; however, it has a 2.5 inch height. In addition, this model gives a 4 to 20 mA output.
These sensors come factory calibrated, but say that it would require an additional purchase of a calibration software: would that be necessary?
As an alternative, Jose designed a custom order for an in-line temperature sensor:
See http://goo.gl/nV1UN for details: the item is priced at $430 and would have a 5-week lead time.
This still has threaded ends and would need threading to barbed adapters.
Note that since this option is a non-catalog order, the order cannot be cancelled or returned unless the item is defective.
The following product will measure temperature in both air and liquid: http://www.omega.com/ppt/pptsc.asp?ref=PR-21&Nav=temc03.
The tip of the probe itself is autoclave-able, but the rest of the device is not, so we would need to place just the tip of the probe into the autoclave.
With the appropriate signal conditioner (see the bottom of the above page), we can get a 4-20 mA output or a 0-10 V output.
The following is a link to a conditioner that is advertised to work specifically with this product to convert the output to a 4-20 mA: http://www.omega.com/pptst/SPRTX-SS.html
The following conditioner is a generic conditioner that can turn several different types of signals into a 4-20 mA or a 0-10V: http://www.omega.com/ppt/pptsc.asp?ref=CCT - this sensor accepts inputs from an RTD temperature probe.
The media that we send through the lung must have the proper oxygen content, which we plan to measure with the following sensors.
The following sensor can determine the oxygen content in a fluid in ppm($280): CP Model #: 35201-56
This sensor has a 3/4” NPT connection so that it can be used in-line with the proper adapters.
It would also require the proper transmitter ($377): CP Model #: 35151-10
This transmitter transmits signals of 4-20 mA.
This sensor - transmitter combo will also take the fluid's temperature at the given location.
This transmitter, however, can only take one probe, and we would therefore need several transmitters.
The 56611-00 would accept 2 probes (but is larger and more expensive) and can work for wither pH or DO.
This would also require the purchase of an additional card for either pH or DO
This model is not autoclave-able, however
The following sensor is autoclave-able (if the cable is removed)($200): CP Model #: 05643-00
This probe does not have any threaded ends or method of connecting the probe in-line.
This probe can be attached to the ($845) CP Model #: 53405-42 in order to give a 4-20 mA output; this setup will not give us any temperature measurement.
We would also need to get the appropriate cables to connect these - see above webpage.
The following probe is also autoclave-able ($790) CP Model #: 05726-00.
This probe says it has threaded ends, although picture does not show - need to double check if can be used in-line.
The probe can be attached to the ($845) CP Model #: 53405-42 in order to give a 4-20 mA output; this setup will also give us temperature measurement.
We would also need to get the appropriate cables to connect these - see above webpage.