Thermal Control System for PCR Reactions
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Solution Overview
Problem
Existing thermal control systems for chemical and biochemical reactions, such as PCR, face challenges with accurate and repetitive temperature cycling due to inefficiencies in Peltier modules, including power loss, mechanical issues, and limited temperature range in water-based systems.
Innovation Solution
A thermal control system that uses a controller to manage the flow of liquids in hot and cold paths to a thermal mount, allowing for precise temperature control by varying flow rates and stopping/start flow, with separate heating and cooling elements and sub-paths within the thermal mount, enabling flexible temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If Peltier modules are used for thermal control, then heating and cooling functions are provided, but power loss occurs and mechanical problems develop during repetitive thermal cycling
Solution Approach 1:
A thermal link is introduced as an intermediary component between the Peltier module and the reaction vessels. The thermal link includes a thermal mass that stores thermal energy and distributes it uniformly across multiple reaction vessels, preventing direct power loss through the Peltier module while maintaining effective thermal control during repetitive cycling operations
2Power
If Peltier modules are used for thermal control, then heating and cooling functions are provided, but mechanical problems occur due to expansion and contraction cycles
Solution Approach 1:
The thermal link acts as a mechanical buffer between the Peltier module and reaction vessels. Its thermal mass absorbs and distributes thermal expansion and contraction stresses uniformly, preventing mechanical damage to individual vessels while maintaining system reliability during repetitive thermal cycling
Solution Approach 2:
The thermal link provides localized thermal management by distributing heat uniformly across multiple reaction vessels. Each vessel receives appropriate thermal input based on its position and thermal contact with the link, preventing localized thermal stress and mechanical failure while maintaining overall system reliability
3Temperature
If water-based thermal control systems are used, then cooling is provided, but temperature range is limited
Solution Approach 1:
The system transitions from water-based thermal control to a Peltier module-based system with adjustable thermal link properties. By changing the thermal parameters of the link (material composition, thermal mass, conductivity), the system achieves extended temperature ranges while maintaining effective cooling capability through the Peltier module
4Stability of the object's composition
If thermal control is provided through well walls, then reactions are not affected, but thermal control accuracy is reduced
Solution Approach 1:
The thermal link serves as an intermediary that directly contacts the reaction vessels, providing accurate thermal control to the vessel bottoms where reactions occur. This maintains reaction integrity by avoiding wall thermal conduction while achieving precise temperature control through the thermal link's controlled thermal mass and conductivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system provides more accurate and efficient temperature control for chemical and biochemical reactions, reducing mechanical stress and extending temperature range capabilities, thereby enhancing the precision and speed of thermal cycling.
Implementation Method 1
the wells are thermally controlled by thermal conductivity through the walls of the wells
Implementation Method 2
a Peltier module essentially consists of semiconductors mounted successively, which form p-n- and n-p-junctions. When switching on a current of one polarity, a temperature difference is formed between the radiators
Data Source
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AI summary
A system (20) for a PCR reaction includes an array of reaction vessels mounted on a thermal mount (21). The thermal mount (21) is provided with a liquid path therein coupled to a cooling liquid input port (22), a heating liquid input port (23) and a liquid output port (24). A pump (38) is used to pump liquid from cooling liquid source (29) either along a cooling liquid path (28) to the cooling liquid input port (22), or via a heating liquid source (31), where the liquid is heated, and along a heating liquid path (30) to the heating liquid input port (23). A temperature sensor (34) measures the temperature of the thermal mount (21) and a processor (27) controls the pump, valves (26) at the input and output ports and valves (41-44) at either side of the pump (38), to control whether heating or cooling liquid is input to the thermal mount, and at what flow rate, in order to obtain the correct temperature of the thermal block (21).