Methods and apparatus to separate biological entities

A method to separate biological entities in a fluid sample comprising the steps of:

• dividing and passing said fluid sample through a plurality of microfluidic devices, wherein said biological entities are separated based on size of said biological entities into a first group and a second group within each of said microfluidic devices by one or more acoustic pressure nodes generated by an acoustic source attached to each of said microfluidic devices, thereby producing a first sample comprising said first group of said biological entities from each of said microfluidic devices;
• passing said first samples from said microfluidic devices into a flow connector, wherein said first samples combine in said flow connector to form a second sample;
• and
• dividing and passing said second sample through a plurality of magnetic devices, wherein said first group of said biological entities in said second sample is magnetically separated to produce a third sample comprising a first sub-group of said first group of said biological entities marked with a magnetic label,
• wherein each of said magnetic devices includes:
• a soft magnetic center pole having a bottom end and a tapered tip end;
• first and second soft magnetic side poles disposed on opposite sides of said soft magnetic center pole and respectively having first and second bottom ends, said first and second soft magnetic side poles respectively having first and second top ends that are bent towards said soft magnetic center pole and are positioned above said tapered tip end;
• a magnetic flux source generating a magnetic flux in said soft magnetic center pole and said first and second soft magnetic side poles;
• and
• a conduit configured to flow said second sample and disposed in a gap formed between said tapered tip end and said first and second top ends,
• wherein said magnetic flux is concentrated from said bottom end to said tapered tip end of said soft magnetic center pole and is divided between said first and second top ends.

A method to separate biological entities in a fluid sample comprising the steps of:

• passing said fluid sample through a magnetic device, wherein said biological entities in said fluid sample are separated by said magnetic device to produce a first sample comprising a first group of said biological entities marked with a magnetic label and a second sample comprising a second group of said biological entities without said magnetic label;
• and
• passing either said first sample or said second sample through a microfluidic device, wherein said either said first group of said biological entities in said first sample or said second group of said biological entities in said second sample are separated based on size of said biological entities into a first sub-group and a second sub-group by one or more pressure nodes generated by an acoustic source attached to said microfluidic device,
• wherein said either said first sample or said second sample is passed from said magnetic device to said microfluidic device through a flow connector, and
• wherein said magnetic device includes:
• a soft magnetic center pole having a bottom end and a tapered tip end;
• first and second soft magnetic side poles disposed on opposite sides of said soft magnetic center pole and respectively having first and second bottom ends, said first and second soft magnetic side poles respectively having first and second top ends that are bent towards said soft magnetic center pole and are positioned above said tapered tip end;
• a magnetic flux source generating a magnetic flux in said soft magnetic center pole and said first and second soft magnetic side poles;
• and
• a conduit configured to flow said sample fluid and disposed in a gap formed between said tapered tip end and said first and second top ends,
• wherein said magnetic flux is concentrated from said bottom end to said tapered tip end of said soft magnetic center pole and is divided between said first and second top ends.