TECHNOLOGY FOR CHANGE

Quantum 'Film' Aims to Replace Digital Imagers

R. Colin Johnson | Date: 03-31-10 | Comments

A new quantum film could replace today's digital imagers with a lower-cost alternative that suspends quantum dots in a black polymer, similar in appearance to traditional photographic film, but which performs like a silicon image sensor.

Photographic film is a polymer with embedded silver grains that, when developed, turn into the dark areas of a photographic �negative.� The disadvantage of photographic film, of course, is that it is write-only and must be processed before it can be scanned into a digital file. By substituting a silicon image sensor for the photographic film, the modern digital camera does its own scanning, thus eliminating the need for old-school film.

Typical CMOS image chips today require light to travel microns through two layers of light-dimming metallization (left). But quantum film placed on the top layer of the chip increases sensitivity by four times.

InVisage (Santa Clara, Calif.) claims its newly invented quantum film can be placed in the same image plane location where light today illuminates the silicon image sensor. Like photographic film, quantum film is composed of a low-cost polymer with embedded nanoparticles; instead of silver grains, quantum film uses semiconductor nanoparticles. The semiconducting nanoparticles absorb light and convert it into an electrical signal, enabling quantum film to serve the same function as a silicon image sensor, but at a much lower price point.

Quantum films offer better sensitivity for ultra-high-resolution sensors that are cheaper to manufacture, according to InVisage. Thus, quantum film is able to create image sensors that are four times as sensitive in the same amount of space, or which are four times smaller with the same sensitivity. The company plans to begin with smaller, lower-cost quantum-film-based image sensors for low-end applications like camera phones. But it also is planning to produce super-high-resolution image sensors that are the same size as today's, but which pack four times as many pixels per unit area.

This quantum film technology was licensed from the University of Toronto, which has for many years been embedding nanoparticles into polymers for applications ranging from inexpensive solar cells to flexible displays. Founded in 2006, InVisage has been quietly developing a low-cost, room-temperature manufacturing process for quantum films with two rounds of financing totaling about $30 million from RockPort Capital, Charles River Ventures, InterWest Partners and OnPoint Technologies.

InVisage's quantum film can be painted onto nearly any surface. For image sensing and display applications, the inexpensive polymer films will replace expensive crystalline silicon. Other applications for its quantum film range from low-power glowing street signs to improved infrared night-vision goggles, as well as super-cheap solar panels and large-area displays that can be sprayed onto nearly any surface, including textiles and clothing.