HPF Carrier/Platelets

High pressure freezing (HPF) carriers, also known as HPF planchettes or HPF plates, are sample holders that hold the sample in shape during high pressure freezing.

HPF carriers are essential components for sample preparation in electron microscopy. The carriers enable biological samples to be frozen quickly and evenly. Compared to chemical fixation structural artefacts are minimized during high pressure freezing. This is crucial for preserving the ultrastructural integrity of samples, making HPF a preferred method in biological and medical research.

HPF carriers are made from a variety of materials, with aluminum and sapphire being the most common.

Aluminum HPF carriers are characterized by their high thermal conductivity, which ensures rapid freezing of samples. These carriers are less expensive and are used for routine applications.

Sapphire HPF carriers, on the other hand, offer exceptional mechanical and chemical resistance. Sapphire is extremely hard and resistant to scratches and mechanical damage, making these carriers durable and ideal for demanding applications. In addition, sapphire is chemically inert and resists most chemical substances, making it suitable for use in aggressive environments. The optical transparency of sapphire is the main advantage as it allows samples to be observed before and after freezing in light microscopes (mostly fluorescence).

HPF carriers with vacuum-deposited or laser-engraved coordinate systems are available for localizing relevant regions of interest (ROI) in samples. These coordinates make it possible to find sample locations in the electron microscope that have previously been identified in the light microscope (CLEM - Correlative Light and Electron Microscopy).