Apparatuses and methods for cutting porous substrates

An apparatus comprising:

• a stripping sleeve;
• a load spring;
• a c-frame support having a die with an inner opening;
• a pillar;
• a puncher seated in the pillar and coaxially located within the stripping sleeve, and having a punch head to cut a biological sample from a substrate,
• wherein:
• the stripping sleeve is to hold the substrate against the die,
• the load spring is to actuate the stripping sleeve to hold the substrate against the die as the punch head passes through the inner opening of the die,
• the punch head is to cut the biological sample by passing through the inner opening of the die,
• the puncher has a diameter at the punch head that is smaller than a diameter at an upper end of the puncher,
• the stripping sleeve is movably coupled to the pillar by one or more guides and one or more channels, the one or more guides being configured to engage with the one or more channels to control relative movement between the stripping sleeve and the pillar,
• when the stripping sleeve holds the substrate against the die, the one or more guides and the one or more channels allow the stripping sleeve to move relative to the puncher to compress the load spring to apply a force to the substrate,
• a bottom end of the stripping sleeve forms a first shoulder against which the load spring presses to actuate the stripping sleeve when the puncher is driven towards the die,
• the load spring surrounds the puncher, and is located between an inner surface of the stripping sleeve and an outer surface of the puncher, and
• the stripping sleeve includes a first tapered head, and wherein the die includes a second tapered head that engages the first tapered head when the puncher is driven downward towards the die, and
• the c-frame support is to hold the die in a fixed position relative to the puncher and the stripping sleeve, and
• wherein the stripping sleeve includes a series of stepped shoulders formed on an inner surface thereof, the series of stepped shoulders including the first shoulder and a second shoulder disposed between the first shoulder and the first tapered head, wherein an inner diameter of the stripping sleeve varies along the inner surface of the stripping sleeve and includes at least a first diameter, a second diameter which is smaller than the first diameter, a third diameter which is smaller than the second diameter, and a fourth diameter which is smaller than the third diameter, the inner diameter transitioning from the first diameter to the second diameter at the first shoulder, the inner diameter transitioning from the second diameter to the third diameter at the second shoulder, and the inner diameter transitioning from the third diameter to the fourth diameter between the second shoulder and the first tapered head.