Syringe Pump for Continuous Cryoprotectant Addition
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Solution Overview
Problem
Current cryopreservation methods for sperm cells involve the addition of cryoprotectants, which can cause stress and cell death due to rapid uptake, particularly with larger cryoprotectant to sperm cell concentration mismatches, and existing methods like drop-wise or bulk additions lack control over flow rates, leading to inefficiencies.
Innovation Solution
A system utilizing a syringe pump with a moveable plunger and dispense tube that allows for continuous and controlled addition of cryoprotectants to sperm cells, preventing droplet formation and minimizing cell stress by submerging the dispense tube or contacting it with the vessel's internal surface, with flow rates determined by equations to optimize the addition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cryoprotectant is added rapidly to sperm cells, then the cryopreservation process is completed quickly, but cell stress increases and cell die-off occurs
Solution Approach 1:
The patent divides the cryoprotectant addition process into multiple discrete steps with specific time intervals. Instead of adding the entire volume at once or through continuous slow addition, the system adds cryoprotectant in segmented portions (e.g., multiple 1 mL additions spaced 15 minutes apart), allowing the sperm cells to gradually adapt to increasing cryoprotectant concentrations while maintaining a manageable total processing time.
Solution Approach 2:
The patent implements periodic addition of cryoprotectant with specific time intervals between additions. The system uses a programmed sequence where cryoprotectant is added, then the system waits for a predetermined period (e.g., 15 minutes) before the next addition. This periodic approach allows cellular adaptation between additions while ensuring complete cryoprotectant incorporation within a defined total time frame.
2Reliability
If large volume of cryoprotectant is added to sperm cells, then sufficient protection is achieved, but the concentration mismatch increases stress on cells
Solution Approach 1:
The patent segments the total cryoprotectant volume into multiple smaller addition steps. Instead of adding the full required volume in one or two large increments, the system divides it into numerous small additions (e.g., adding 1 mL at a time over multiple steps). This segmentation ensures that at each step, the concentration mismatch remains manageable, reducing cellular stress while achieving the necessary total concentration for effective cryopreservation protection.
3Device complexity
If traditional drop-wise or bulk addition methods are used, then equipment complexity is low, but flow rate control is poor leading to cell die-off
Solution Approach 1:
The patent incorporates feedback control through a weighing mechanism that continuously monitors the mass of the vessel during cryoprotectant addition. The system compares the actual mass against the target mass and automatically adjusts the addition rate or pauses addition when the target is reached. This feedback loop ensures precise control over the total volume added and the timing between additions, eliminating the need for complex flow rate controllers while achieving high precision.
Data Source
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AI summary
An integrated system and method for preparing sperm cells to improve their survivability during cryopreservation are described herein. The system features a vessel, a controlled dispenser, and a dispense tube. The dispense tube has a first end fluidly connected to the dispenser and a second end disposed inside the vessel. The second end can be submerged in the sperm cell fluid. The controlled dispenser may be a syringe pump that includes a syringe for containing a cryoprotectant and a pushing mechanism for displacing the syringe. The syringe pump is configured to discharge the cryoprotectant through the dispense tube and into the vessel, thereby dispensing the cryoprotectant into the sperm cell fluid. Mixing of the fluids is achieved using a shaker table agitation.