Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR) and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms.

A compact piezoresistive microcantilever platform integrated by MEMS technique provides a convenient and reliable approach for biochemical detection. In contrast to the conventional double free-standing piezoresistive cantilever beams of heterogeneous sensing surfaces, a single free-standing piezoresistive microcantilever sensor was first proposed with the elimination of interference of chemical effect. The single beam piezoresistive sensor which is temperature-sensitive was well controlled within ±0.2°C by introducing the novel method of self elimination of thermal effect. This new approach maintains device compactness with no additional use of bulky temperature-controlled apparatus, and significantly reduces noises of temperature coefficient of resistance (TCR) and bimorph effect. The C-reactive protein (CRP) detection of the microcantilever biosensor with self elimination of thermal effect was verified with the concentration of 100 μg/mL in a room-temperature environment.