Omron E3T-ST21 2M Ultracompact Photoelectric Sensor

USD 74.54

Ultracompact side-view through-beam sensor with a 300mm sensing range and built-in amplifier. Features a 1ms response time, NPN Light-ON output, and IP67-rated PBT housing.

SKU Omron-E3T-ST21 2M Category
Industrial Sensors > Photoelectric Sensors

Omron E3T-ST21 2M Ultracompact Photoelectric Sensor

Model Identifier E3T-ST21 2M
Official Part Number E3T-ST21 2M
GTIN Standard NA

Technical Overview

The Omron E3T-ST21 2M is an ultracompact, side-view through-beam photoelectric sensor featuring a built-in amplifier. Designed to reliably detect opaque objects as small as 2 mm in diameter, it utilizes a 650 nm red LED light source and achieves a sensing distance of up to 300 mm. Operating on a 12 to 24 VDC supply voltage, the sensor offers an NPN Light-ON digital output and rapid 1 ms response times. Housed in a durable thermoplastic P.B.T. enclosure, it delivers IP67-rated ingress protection, making it highly suitable for space-constrained applications in industrial environments that demand robustness and a minimal footprint.

Key Features

  • Ultracompact side-view housing (14.6 x 7 x 9.5 mm) designed for extremely tight space constraints.
  • Through-beam sensing method achieving a robust maximum distance of 300 mm.
  • Reliable detection of small opaque objects down to 2 mm in diameter.
  • Built-in amplifier delivering a 26.4 VDC max NPN Light-ON output configuration.
  • Fast response time of 1 ms maximum, ideal for high-speed automated processes.
  • Pre-wired with a 2-meter cable with bare flying leads for direct connection.
  • IP67-rated enclosure constructed from durable Thermoplastic P.B.T. polymer.

Ultracompact footprint with an integrated amplifier, M2 mounting, and IP67 ingress protection.

Technical Specification Matrix

ParameterValue
Sensing Distance300 mm
Sensing MethodThrough-Beam
Output TypeNPN Open Collector (Light-ON)
Light SourceRed LED (650 nm)
Minimum Detectable ObjectOpaque, 2 mm dia. min.
Supply Voltage12 to 24 VDC ±10%
Current Consumption30 mA max total (Emitter: 10 mA max, Receiver: 20 mA max)
Response Time1 ms max (Operate or Reset)
Degree of ProtectionIP67
Connection MethodPre-wired, 2 m cable
Housing MaterialThermoplastic P.B.T. Polymer
Operating Temperature-25 to +55 °C
Dimensions (H x W x L)14.6 mm x 7.0 mm x 9.5 mm

Industrial Applications

1. Semiconductor Wafer Detection in Cassettes

In cleanroom automated material handling systems, detecting the presence or protrusion of thin semiconductor wafers requires precision within highly confined spaces. The E3T-ST21 easily fits into narrow robotic end-effectors or cassette racks due to its ultra-compact 7mm width. Its 2mm minimum target detection handles standard wafer edges reliably, and the 1ms response ensures high-throughput scanning during robot axis movements.

Problem Solved

Prevents robotic collisions by reliably detecting wafer placement errors in microscopic clearances where standard-sized optical sensors cannot fit.

Semiconductor HandlerWafer ProtrusionM2 Mounting1ms Response TimeThrough-beam Sensing

2. High-Speed Component Counting in Packaging

For automated blister packaging or parts counting machinery, verifying the drop of small components ensures accurate fill volumes. The 1ms response time matches the speed of high-throughput dropping mechanisms, while the 300mm range allows the emitter and receiver to straddle wider conveyor or sorting chute zones without signal loss.

Problem Solved

Eliminates under-packing errors and missed counts caused by fast-moving parts falling through wide sorting chutes undetected.

Blister PackagingParts CountingNPN Open Collector300mm RangeOpaque Object Detection

3. Micro-part Verification in Medical Device Assembly

Automated assembly lines for medical syringes or catheters require the detection of tiny sub-components before sealing. With its 650nm red LED providing clear visible alignment and the ability to detect 2mm opaque objects, this sensor guarantees components are seated. Its IP67 rating additionally protects against the washdown or sanitization processes common in sterilized machine environments.

Problem Solved

Rejects misassembled medical products prior to final packaging, ensuring critical quality control in wet or sterilized assembly cells.

Medical Assembly LineIP67 WashdownVisible Red LEDThermoplastic Housing2mm Minimum Target
Select your currency