Design Of A Ketamine Rapid Detection System Based On The Ultrasonic Atomizer Combined With A Gas Chromatography-surface Acoustic Wave Sensor

As a high-efficient anesthetic in clinic,ketamine has been extensively abused for entertainment over the past few years,causing a series of social problems.Therefore,the importance of establishing a method for rapid and accurate detection of ketamine has become increasingly prominent.Based on the ultrasonic atomizer combined with a Gas Chromatography-Surface Acoustic Wave sensor(GC-SAW),this paper proposed an on-site system for rapid detection of ketamine.The system consists of three modules:pretreatment module,gas chromatography(GC)module and surface acoustic wave(SAW)sensor detection module.For most of the existing methods,pretreatment of ketamine samples is time-consuming and complex before detection.By using an ultrasound atomizer to convert liquid samples of ketamine into aerosol form,this paper proposed a novel method to complete the pretreatment process within 30s.The structure of pretreatment module was designed.According to the results of velocity field simulation analyses in atomization chamber,the injection point was selected.A suitable working voltage for the pretreatment module was determined through experiments.The separation of components in ketamine samples was realized by designing heating method in GC module.Based on GC,metallic column was used and the directly resistive-heating method was designed to improve heating efficiency and portability of the system.The heating rate of GC module could reach 10℃/s and the whole heating process was able to be done within 30s.With the designed structure and heating method,the GC module had a temperature control accuracy of 0.1℃.A resonant SAW sensor which is sensitive to micro mass was used for component detection in SAW detection module.In order to provide a stable working environment for SAW sensor,a temperature-tunable air chamber was designed.The air chamber had a temperature control accuracy of 0.2 ℃.Detection circuit formed by SAW sensor oscillation circuit,frequency mixing circuit and frequency measurement circuit was designed.The designed frequency measurement circuit had an accuracy of 0.5Hz.Upon the realization of three modules,the system structure and the detailed assembly layout were designed.Three modules of the system were assembled.Considering the situation of local overheating during operating,cooling solutions were proposed and optimized by thermodynamics simulation analysis of the whole system.Finally,a portable ketamine rapid detection system was completed.Tested with the standard ketamine samples,this system showed a good linear correlation(R2=0.9481),with a detection limit of O.lug/ml.Besides,for a single sample,the detection time was reduced to 1 minute.This system was thus proved to be feasible,reliable and accurate for ketamine detection.