Miniaturized thermal cycler

A structure for thermal cycling, comprising:

• a frame made of a thermally conductive material and having an open interior area,
• suspended within said open area, a plurality of chambers in the form hollow bodies having first and second opposing ends each of which is connected to the frame through a thermally conductive beam;
• within each chamber, at each end, a heat transfer area through which all heat that flows in and out of the chamber passes;
• within each chamber, two heating elements, one each symmetrically disposed around one each of said transfer areas;
• for each chamber, a first fluid bearing channel that enters the chamber at its first end through a first orifice located within the transfer area at that end;
• for each chamber, a second fluid bearing channel that enters the chamber at its second end through a second orifice located within the transfer area at that end;
• within each chamber, at least one temperature sensor per heating element, said sensor being located close to said heating element, and
• means for sending fluid into, and removing fluid from, each chamber through said channels and orifices whereby fluid flow into and out of each chamber is individually controllable.

A structure for thermal cycling, comprising:

• a frame made of a thermally conductive material and having an open interior area,
• suspended within said open area, a plurality of chambers in the form hollow bodies each being connected to the frame through a single thermally conductive beam;
• within each chamber a heat transfer area, having an interior surface, through which all heat that flows in and out of the chamber passes;
• within each chamber, a heating element symmetrically disposed inside the transfer area;
• for each chamber, a first fluid bearing channel that enters the chamber through a first orifice located within the transfer area;
• for each chamber, a second fluid bearing channel that enters the chamber through a second orifice located within the transfer area;
• within each chamber, a baffle that is parallel to the surface of the transfer area and that is orthogonally connected to the transfer area by a sheet of material that comes between the first and second orifices;
• within each chamber, at least one temperature sensor per heating element, said sensor being located close to said heating element;
• and
• means for sending fluid into, and removing fluid from, each chamber through said channels and orifices whereby fluid flow into and out of- each chamber is individually controllable.

A process for manufacturing a thermal cycler, comprising the sequential steps of:

• providing a silicon wafer having upper and lower surfaces,
• in said upper surface, etching two inner and two outer trenches to a first depth, said inner tenches having a first width and said outer trenches having second width;
• forming a first dielectric layer on said upper surface, including said trenches;
• depositing a layer of material suitable for use as a sensor and as a resistive heater,
• patterning and etching the material layer to form temperature sensors and heater elements;
• in said upper surface etching, to a second depth, two top preliminary trenches having a third width, each being located between an inner trench and an outer trench;
• patterning and etching said upper surface whereby a chamber trench, having a fourth width and located between said inner trenches, is formed to a third depth and the top preliminary trenches have their depth increased to a fourth depth;
• forming a second dielectric layer on said upper surface, including all trenches;
• patterning and etching the lower surface of the wafer to form an under-trench that is wide enough to slightly overlap the top preliminary trenches, to a depth such that the top preliminary trenches extend through said lower surface and, within the chamber trench, the wafer has a thickness that is between about 30 and 100 microns,
• providing a sheet of dielectric material and micro-machining said sheet to form holes in selected locations;
• and
• bonding the sheet to the wafer thereby forming a hermetically sealed chamber that is thermally isolated from the wafer.