Patent ID: 11921028
Assignee: MENARINI SILICON BIOSYSTEMS S.P.A.
Field: Measurement (Instruments)
Classification: CPC G  B | IPC B  G

Claim 6:
7. An apparatus for optical analysis of particles contained in suspension in a fluid, comprising:
a microchamber comprising an internal volume delimited by interior surfaces of oppositely disposed first and second sheets, the internal volume being adapted to contain the particles contained in suspension in the fluid, the first and second sheets defining bottom and top surfaces of the microchamber, an exterior surface of the second sheet defining an optical inspection surface through which the particles can be optically inspected;
a cooling device thermally coupled with the first sheet and being adapted to cool the fluid when contained in the internal volume of the microchamber to a first temperature and maintain the fluid at the first temperature during optical inspection;
a thermal flow generator arranged to generate a thermal flow across the optical inspection surface to heat the optical inspection surface to a second temperature and maintain the optical inspection surface at the second temperature during operation of the apparatus for optical inspection of the particles in suspension; and
an optical inspection device for optical analysis of the particles in suspension in the internal volume, the optical inspection device arranged to optically view the particles through the second sheet, wherein:
the first temperature is below ambient temperature,
the second temperature is higher than a temperature of condensation of ambient humidity contained in the air which surrounds the optical inspection surface,
the first sheet has a thermal conductivity that is at least one order of magnitude higher than the second sheet, and
the second sheet has a thickness determined by, H
   
    l
    ⁢
    i
    ⁢
    d
   
  
  >
  
   
    (
    
     
      
       T
       
        d
        P
       
      
      -
      
       T
       0
      
      -
      
       Δ
       ⁢
       
        T
        max
       
      
     
     
      Δ
      ⁢
      
       T
       max
      
     
    
    )
   
   ⁢
   
    (
    
     
      σ
      lid
     
     
      σ
      
       b
       ⁢
       u
       ⁢
       f
      
     
    
    )
   
   ⁢
   
    H
    c
   
  
 

where Hlid is the thickness of the second sheet, Tdp is the temperature of condensation of ambient humidity contained in the air which surrounds the optical inspection surface, To is an operating temperature desired inside the microchamber, ΔTmax is the maximum increase in temperature tolerable inside the microchamber relative to a target operating temperature, σlid is the thermal conductivity of the second sheet, σbuf is a thermal conductivity of the fluid to be contained in the microchamber, and Hc is a thickness of the microchamber as measured by the distance between the interior surfaces of the first and second sheets, wherein ΔTmax=(Tbuf−To)max and Tbuf is the temperature of the fluid.