Signotec Sigma

The signotec Sigma is a compact pad for electronically capturing handwritten signatures, equipped with a 4" (10.5 cm) monochrome LCD screen. The signature is displayed on the device screen in real time, allowing the user to monitor its appearance during signature creation. Its small size, weight of approximately 180 g, and direct USB power supply allow the device to be used both at stationary stations, such as reception desks, banks, or customer service points, and in mobile applications.

The Sigma records not only the pen's position but also the pressure and time, saving signature data in a 4D format: x, y, z, t. The sampling rate is 500 Hz, and the device recognizes 1024 pressure levels. The pad supports AES and RSA security mechanisms and can perform cryptographic operations related to the signature within the device.

Technical Specifications

Manufacturer: signotec GmbH, Germany.
Model: signotec Sigma.
Device type: pad for electronic signature capture. Display: 4" / 10.5 cm monochrome LCD.
Backlight: Optional LED backlight.
Display resolution: 320 × 160 pixels.
Document scrolling function on the pad: no.
Sensor technology: RTP – Resistive Touch Panel.
Surface: Special foil surface designed for the RTP sensor.
Active signature area: 91 × 45 mm.
Sensor resolution: 4096 × 4096 points, corresponding to approximately 2214 × 1130 ppi.
Pressure levels: 1024.
Sampling frequency: 500 Hz.
Recorded signature data: 4D – x, y, z, t, i.e., movement coordinates, pressure, and time.
Pen: Special battery-free pen with spring-loaded, Replaceable tip.
The pen is connected to the device with a cable.
Declared sensor surface durability: approximately 1 million signatures.
Basic interface: USB.
USB cable length: approximately 2 m.
USB cable: permanently attached to the device.
Power supply: directly via USB, no separate power supply required.
Optional FTDI/vCOM interface enables operation in Remote Desktop and Citrix environments, among others.
The USB and FTDI/vCOM versions cannot be switched later via software—the appropriate version must be selected at the time of purchase.
TCP/IP network support: possible with the optional signotec USB-Ethernet adapter.
Citrix Virtual Channel support: possible with the appropriate signotec driver.
Encryption: AES and RSA.
Secure Mode: allows for real-time signature display without sharing useful biometric data.
Supported hash algorithms: the manufacturer provides, among others, SHA-256 and SHA-512.
Ability to encrypt RSA signature biometrics within the device.
Ability to perform RSA signatures on the pad; signotec documentation indicates support for this feature for Sigma from firmware 1.16.
Each device is supplied with an individual RSA certificate for the device's signature function.
Dimensions: 160 x 120 x 10 mm.
Weight: approximately 180 g.
Indication: two-color status LED.
Ability to save the image displayed in standby mode.
Housing color and logo printing can be personalized upon request.
Standard manufacturer's warranty: 2 years.
Included: signotec Sigma pad, USB cable, pen with lanyard/cord, and free signoSign/2 Lite software.

Software Required for Operation

The pad itself requires a compatible application that initiates the signing process and receives data from the device. Simply connecting the device to a USB port does not yet enable document signing.

For standard local operation with a Windows computer, the device can be connected without installing an additional USB driver. One of the compatible software solutions is then required.

The simplest option is the freely available signoSign/2 Lite, designed for opening, editing, and signing PDF documents. It enables features such as creating signature fields and securely capturing signature data.

For professional use, signoSign/2 Pro is available, providing broader support for document processes, automation, archiving, and advanced signature mechanisms.

The Adobe Acrobat Plug-in is also available, allowing you to sign documents directly in Adobe Acrobat Reader/Pro, as well as signoPAD-API/SDK interfaces enabling Sigma integration with your own application. To use the pad directly with a web application, the manufacturer requires the local signoPAD-API/Web component to be installed.

For the Sigma version with the FTDI/vCOM chip, a free FTDI driver is required. This applies to scenarios including those using a virtual COM port and terminal environments.

Advantages

Compact dimensions and low weight. At 160 x 120 x 10 mm and approximately 180 g, the Sigma takes up minimal space at the workstation and can be used mobile.

Excellent signature capture quality for this class of device. 500 Hz sampling, 1024 pressure levels, and x/y/z/t parameter recording allow for the recording of dynamic signature properties, not just an image.

Built-in display. The signer sees their signature directly on the device, a feature not offered by the cheaper Sigma Lite.

Extensive security features. AES, RSA, the ability to encrypt biometric data and perform RSA operations within the device reduce the need to process sensitive information solely on the computer.

No batteries in the pen and no separate power supply. Simplifies operation – the pad and pen do not require charging, and the device is powered via USB.

Free startup software. signoSign/2 Lite is included with the device, so for basic PDF signing, you don't need to purchase an additional application.

Good integration capabilities. The manufacturer provides APIs, web application solutions, Adobe integration, and Citrix/RDP and Ethernet compatibility.

Disadvantages and limitations

Small, monochrome screen of 320 x 160 pixels. This is sufficient for signature previews and simple messages, but not suitable for conveniently presenting entire documents or more complex forms. Models with larger screens, such as the signotec Delta, allow for full-page document viewing.

No scrolling function. The user cannot view subsequent sections of the document on the Sigma before signing.

Older RTP technology and a foil surface. The manufacturer specifies the Sigma's durability at approximately 1 million signatures, while the newer signotec Zeta with an ERT sensor and tempered glass surface is claimed to have a durability of approximately 30 million signatures. This is a significant difference in a high-volume transaction environment.

Fixed USB cable. Cable damage can be more problematic for service than with a device with a detachable cable. The manufacturer confirms that the cable is permanently attached to the device.

The choice of USB or FTDI should be made before purchase. The manufacturer clearly states that the USB mode cannot be changed to vCOM or vice versa. Therefore, when deploying in Citrix/RDP, it is necessary to select the correct option beforehand.

For more advanced applications, additional, paid software is required. The free signoSign/2 Lite is designed primarily for basic PDF processes; advanced automation, professional document processing, and some integration features require the Pro version or other components.