Microheater Array Research Articles

Low-voltage and low-power optimization of micro-heater and its on-chip drive circuitry for gas sensor array

Low-voltage and low-power design is the key issue for the portable electronics applications and has become the major concern for the system design. Integrated gas sensor array allows the monolithic realization of multi-species gas sensing systems. This paper reports the developments of Si-based micro-machined micro-heater array with extremely low-power consumption, low-voltage operation, and CMOS compatibility, and low-voltage and low-power CMOS drive circuitry for the micro-heaters that can provide large drive current and voltage swing, and heater temperature is continuously adjustable in the full temperature range.

Use of Microhotplate Arrays as Microdeposition Substrates for Materials Exploration

An approach for high-throughput rapid screening of chemical vapor deposition (CVD) materials using micromachined silicon microheater arrays is described. To illustrate this approach, titanium dioxide was deposited by CVD, using titanium(IV) nitrate and titanium(IV) isopropoxide at temperatures between 130 and 815 °C. Deposition was confined to the microhotplate elements within 4- and 16-element arrays. Film microstructure was examined by scanning electron microscopy. In situ electrical measurements were made with integrated microcontacts during the deposition of TiO2 using titanium(IV) isopropoxide. A novel approach using temperature-programmed deposition with temperature ramp rates up to 800 °C/s was also employed for microstructure modification during deposition. Additionally, the steep temperature gradients present on the microhotplate supports have been demonstrated to provide an excellent platform for investigating temperature-dependent microstructures.

Feasibility study on a contact-less direct thermal printing with electrothermal SPICE simulation

A new concept for making contact-less direct thermal printing for facsimile is proposed and evaluated in this article. The concept is based on the fact that air molecules can be a good thermal conduction medium capable of transferring the heat efficiently from a micro-heater to a thermal marking paper, if both in close proximity. The micro-heater can be made of single-crystal silicon by micromachining technology, hence the associated CMOS driving circuits can be fabricated monolithically with the heater to exempt from the tedious work of numerous wire bonding. An illustrative device of integrated micro-heater array in 200 dpi resolution has been fabricated, characterized and evaluated for the new printing application. A thermal model of the device has also been set up and studied of its dynamic behaviors using the existing electrothermal SPICE package. The result of simulations indicates that efficient energy transfer of more than 40%, much better than the conventional performance, can be achieved with a practical 1 μm air gap. This and other additional advantages described in the article indicates that, in principle, the contact-less direct thermal printing is feasible and the monolithic silicon micro-heater array can be an excellent device for this application.

Computer control of fiber Bragg grating spectral characteristics using a thermal head

We present a new technique for arbitrarily controlling the temperature distribution in fiber Bragg gratings (FBG's) to control their spectral characteristics. A thermal head consisting of a microheater array, driven with computer control signals is used as a controlling device. Various spectral characteristics including a chirped grating and a transmission filter are demonstrated using a single unchirped grating. An effective improvement in response time constant of thermal control was observed on bonding of the fiber grating to thermal head (18 ms), in comparison to that without bonding (40 ms). The measured results did not show any hysterisis. Reliability studies of this technique are also reported. The same technique is further used for the dual wavelength operation of an Er-doped fiber laser.