Patent Application
20080047438
Embodiments of the liquid impingement unit are described relative to the several views of the drawings. Where appropriate and only where identical elements are disclosed and shown in more than one drawing, the same reference numeral will be used to represent such identical elements.
Embodiments of the present invention are directed to a modified liquid impingement unit configured to automatically refill the collection vessel with buffer solution on a periodic basis. In this manner, the volume of the buffer solution is automatically maintained within a desired range over the course of operation of the liquid impingement unit. This desired range can be maintained over an indefinite period of time. The liquid impingement unit includes a collection vessel, an air nozzle, and a vacuum tube. A first volume of buffer solution is added to the collection vessel. A first end of the air nozzle and a first end of the vacuum tube are sealed within the collection vessel. A fluid delivery tube is positioned within the vacuum tube such that a first end of the fluid delivery tube is also positioned within the sealed collection vessel. In some embodiments, the first end of the fluid delivery tube extends into the buffer solution within the collection vessel.
External to the sealed collection vessel, the vacuum tube includes an aperture through which the fluid delivery tube exits. A second end of the vacuum tube is coupled to a vacuum pump. A second end of the fluid delivery tube, which is external to the vacuum tube, is coupled to a fluid pump. The fluid pump is configured to deliver a second volume of buffer solution from a buffer solution container to the collection vessel via the fluid delivery tube. A control module provides control signals to the fluid pump such that the fluid pump delivers the second volume of buffer solution. In this manner, additional buffer solution is automatically provided to the collection vessel according to control signals provided by the control module. In some embodiments, the control module is configured to instruct the fluid pump to deliver the second volume on a periodic basis. This period is determined based on a known evaporation rate of the first volume of buffer solution within the sealed collection vessel. Alternatively, one or more sensors are mounted within the collection vessel to monitor the first volume of the buffer solution within the collection vessel. Once the first volume decreases below a predetermined threshold, the control module instructs the fluid pump to deliver the second volume of buffer solution to the collection vessel. Still alternatively, the fluid pump delivers a continuous stream of buffer solution to the collection vessel. The continuous stream is provided at a determined rate based on the known evaporation rate.
A general function of the liquid impingement unit is to receive airflow including airborne particles, direct the airflow to the buffer solution within the collection vessel where the airborne particles are collected in the buffer solution, then periodically remove the buffer solution including the collected particles for processing. The particle collection efficiency of the liquid impingement unit decreases as the volume of buffer solution decreases. Therefore, in order to maintain efficiency of the liquid impingement unit, the volume of the buffer solution is maintained within an acceptable range.
The first end of the air nozzle 54 is positioned above and proximate to the surface of the buffer solution 60. The exact distance between the first end of the air nozzle 54 and the buffer solution surface is variable based on the volume of the buffer solution 60. The position of the first end of the air nozzle 54 relative to an initial volume of the buffer solution 60 is determined according to the airflow rate out of the air nozzle 54 and/or the dimensions of the collection vessel 52. The distance can also be experimentally determined based on a desired particle collection efficiency. As the volume of the buffer solution 60 decreases due to evaporation, the relative distance between the surface of the buffer solution 60 and the first end of the air nozzle 54 varies. In an alternative embodiment, the first end of the air nozzle is in contact with the surface of the buffer solution or is submerged beneath the surface of the buffer solution. In the alternative embodiment where the first end of the air nozzle 54 is initially submerged within the buffer solution 60, the surface of the buffer solution 60 may fall below the first end of the air nozzle 54 over the course of operation such that the first end is no longer submerged within the buffer solution 60.
A lid 58 seals the collection vessel 52 such that the first end of the vacuum tube 56 and the first end of the air nozzle 54 are hermetically sealed within the collection vessel 52. In some embodiments, an o-ring is positioned between the vacuum tube 56 and the lid 58 and an o-ring is positioned between the air nozzle 54 and the lid 58 to seal the unit. The fluid delivery tube 62 and the vacuum tube 56 are configured such that the fluid delivery tube 62 enters the vacuum tube 56 through an aperture 74 within the vacuum tube 56, and runs the remaining length of the vacuum tube 56 into the collection vessel 52, thereby circumventing the lid 58. The fluid delivery tube 62 exits the first end of the vacuum tube 56 and extends into the buffer solution 60. In some embodiments, the first end of the fluid delivery tube 62 extends beyond the first end of the vacuum tube 56, but not into the buffer solution 60. In some embodiments, the first end of the fluid delivery tube 62 co-terminates with the first end of the vacuum tube 56.
A second end of the fluid delivery tube 62 is coupled to the fluid pump 64. The fluid pump 64 is coupled to the buffer solution container 66. In operation, the fluid pump 64 pumps buffer solution from the buffer solution container 66 through the fluid delivery tube 62 and into the collection vessel 52. In some embodiments, the fluid pump 64 pumps a set volume of buffer solution on a periodic basis. Alternatively, the fluid pump 64 continuously pumps buffer solution at a set rate.
The liquid impingement system 150 automatically maintains the volume of buffer solution 60 in the collection vessel 52 within a determined range. The liquid impingement system 150 is also configured to automatically initialize the system with an initial volume of buffer solution 60. To initialize the system, the lid 58 is sealed onto the collection vessel 52, where the buffer solution has yet to be added. A start sequence is initiated and the control module 70 signals the fluid pump 64 to deliver a defined initial volume of the buffer solution from the buffer solution container 66. In some embodiments, the start sequence is initiated by a start command provided by the user or provided by an externally coupled system. After the initial volume of buffer solution is added to the collection vessel 52, an air collection system including the liquid impingement system is actuated to start delivering air through the air nozzle 54. After a set period of time, the control module 70 instructs the fluid pump 64 to pump the second volume of buffer solution into the collection vessel 52, thereby maintaining the volume of buffer solution 60 in the collection vessel 52 within the determined range.
Although the embodiments of the liquid impingement units described in relation to
The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. The specific configurations shown and the methodologies described in relation to the liquid impingement unit are for exemplary purposes only. Such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention.
