ASD12-N Absorption Probe

Single Channel Absorption Probe

The ASD12-N absorption probe has a durable LED light source for direct installation into laboratory bioreactors and disposable bioreactors for measuring cell growth and optical density. The probe is available in three different lengths to fit any vessel and is suited for sterilization / autoclaving procedures.

Used For

  • Turbidity (optical density) scale:
    • CU (concentration units)
  • Absorption based monitoring of
    • cell growth and bacterial fermentation (Biotech, Pharma)
    • algae concentration (Biotech, Pharma, food)

The ASD12-N absorption probe is designed for the use in pilot scale fermenters or bioreactors including single-use bioreactor bags to precisely measure the growth of microbial or cell cultures as a function of NIR absorption. The ASD12-N is autoclavable and mounts conveniently through any headplate or aseptic connector with a PG13.5 threaded port. The sensor is available in three different insertion depths with 1, 5 or 10 mm optical path lengths. Shorter optical path lengths are typically used for dense cell cultures such as bacterial and yeast cultures. Longer OPL’s are used for less dense cell cultures e.g., mammalian cells and dissolution / precipitation / crystallization reactions.


LED light source for slim sensor design
Fits into standard 12 mm ports

Various optical path lengths (OPL) are available:1 , 5 and 10 mm
Optimal sensors for any OD range

Selectable sensor length from 110 to 315 mm plus OPL
Flexibility to mount in a broad range of vessel sizes

Sterilisation / autoclaving
Ensures sterility and minimizes contamination risks

Validation accessories
Easy on-site / on-demand verification
  1. OPL
  2. Sapphire windows
  3. Detector
  4. Daylight filter
  5. LED light source

No window gaskets used

Measurement principle

1- Channel Absorption of light

Measurement wavelength(s)

840 - 910 nm


1 silicon photodiode (hermetically sealed)

Measuring Range

any measuring range between:

  • 0 - 0.05 to 4 CU
Optical path length

1, 5 or 10 mm others on request


CU (concentration units) application specific calibration

Light source

Hybrid LED (hermetically sealed), 5.4 V DC, 100 mA

typical life span: approx 10 years



Process Adaption

wetted parts: stainless steel 1.4435 (SS 316L) dF < 1 %, BN2

surface: N5: Ra < 0,4 μm (16 µinch) - electropolished

Port connection

Fermenter head plates

diameter:12 mm

thread:PG 13.5

Port gasket

O-ring 11.00 x 3.00 mm


Insertion depth

110 mm + OPL

215 mm + OPL

315 mm + OPL

others on request

Process pressure


(+/- 0.5 bar) (+/- 7.25 psi)


Sapphire (seal-less)

Installation accessories

Adapter PG 13.5 Variable depth

Adapter M 26 x 1 - PG 13.5

Temperature Ratings
Process temperature

permanent:5 - 50°C (41 - 122°F)

Ambient temperature

operation:0 - 40 °C (32 - 104 °F)

transport:-20 - 70 °C ( -4 - 158 °F)

Sterilization conditions

Sterilization must be performed outside the process and the ASD must be disconnected from the power source

(autoclaving possible without cable)

max. pressure: 4 bar (58 psi)

max. temperature: 135 °C (275 °F) (max. 60 min./day)

Pressure and temperature ratings specified herein may be subject to limitations - see instruction manual. The appropriate choice of material for all wetted parts is the sole responsibility of the user. Data given are subject to changes without prior notice.

Speed / Spare Parts

Installation Kit ASD12 PN: 1200-3413-0001-00

Installation Kit ASD12

PN: 1200-3413-0001-00

O-Ring 11.00 x 3.00 EPDM (FDA) (4) PN: 1203-0004-0044-03

O-Ring 11.00 x 3.00 EPDM (FDA) (4)

PN: 1203-0004-0044-03

C4000 - C8000 Product Information

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