To ensure that liquid flows out when you inject it, you would need to create a system that allows for controlled and directed flow. Here are a few possible solutions:
Use a syringe with a plunger: A syringe typically has a plunger that can be pulled back or pushed forward to control the flow of liquid. Pulling the plunger back creates a vacuum, while pushing it forward forces the liquid out of the needle.
Employ a pump or pressure system: A pump or pressure system can be used to generate pressure that pushes the liquid out. This can be achieved through mechanisms like air pressure, hydraulic pressure, or mechanical pumping.
Utilize gravity: By positioning the liquid container above the injection point, you can rely on gravity to create a downward flow. This approach is commonly used in systems such as intravenous (IV) drips, where the liquid flows from an elevated bag to the patient's body.
Employ a specialized device: Depending on the specific application and requirements, there may be devices designed for specific liquid injection scenarios. For instance, some medical devices, such as insulin pens, are engineered to ensure the liquid is expelled upon injection.
It's important to note that the design and implementation of such systems can be complex and require careful consideration of factors like pressure, flow rate, and safety. If you have a specific application or context in mind, it may be beneficial to consult with experts or professionals in the relevant field, such as medical professionals, engineers, or technicians, who can provide tailored advice and guidance.