Printed sensors

S. Andreescu, V. Magearu, A. Lougarre, D. Fournier, and J.L. Marty, Immobilization of enzymes on screen-printed sensors via a histidine tail. Application to the detection of pesticides using modified cholinesterase. Anal. Lett. 34, 529-540 (2001). 

Furthermore, other solid-state sensors have been developed and introduced, ranging from thin film and screen-printed sensors to ceramic sensors and - latterly polymeric sensors. 

In some applications, silver/silver chloride or calomel electrodes are considered cumbersome to use and maintain. More importantly, they are extremely difficult to miniaturize particularly with regard to their combined use with potentiometric membrane electrodes (see Section 18a.4.5.4) that have been fabricated into highly miniaturized and compact screen-printed sensor arrays for clinical use. Thus, several reference electrodes are manufactured with the same polymeric materials that are needed to design the responsive ion-selective membranes [7]. Incorporation of suitable active agents into such membranes leads to potentiometric responses that are ideally independent of the sample... 

A.L. Hart, C. Matthews and W.A. Collier, Estimation of lactate in meat extracts by screen-printed sensors, Anal. Chim. Acta, 386 (1999) 7-12. M. Albareda-Sirvent and A.L. Hart, Preliminary estimates of lactic and malic acid in wine using electrodes printed from inks containing sol-gel precursors, Sens. Actuators B Chem., 87 (2002) 73-81. 

W. A. Collier, P. Lovejoy and A.L. Hart, Estimation of soluble L-lactate in dairy products using screen-printed sensors in a flow injection analyser, Biosens. Bioelectron., 13 (1998) 219-225. 

N. Kirsch, J.P. Hart, D.J. Bird, R.W. Luxton and D.V. McCalley, Towards the development of molecularly imprinted polymer based screen-printed sensors for metabolites of PAHs, Analyst, 126 (2001) 1936-1941. 

S. Laschi, I. Palchetti and M. Mascini, Gold-based screen-printed sensor for detection of trace lead, Sens. Actuators B Chem., 114 (2006) 460-465. 

Extraction of minced meat into buffer was used immediately prior to determination of lactate in meat by screen-printed sensors mounted in a FIA system [17]. The sensors were similar in design to those used for dairy product analysis [31] although they were constructed completely by screen-printing rather than having the outer membrane applied... 

A.L. Hart, C. Matthews and W.A. Collier, Estimation of lactate in meat extracts by screen-printed sensors, Anal. Chim. Acta, 386 (1999) 7-12. 

Total solid content 12 PVC membrane sensors Screen-printed sensors, FIA Water, beverages [34]... 

Catechines, sugars+arginine aminoacid 30 sensors+biosensors Screen-printed sensors, FIA Teas [98]... 

Printed sensors Organic conductors, carbon-based inks. Under development. 

An area of recent interest for printed electronics is printed sensors. The general concept is to develop simple sensors for product quality monitoring, etc., that use small numbers of transistors with very low performance. This is a diffuse area that is still developing, and therefore will not be discussed here. However, it is important to note that many of the concerns that apply to displays and RFID apply here as well, and therefore, the main technology driver for most areas of printed electronics continues to be the printed transistor. 

Figure 3. The increase in sensor performance with decreasing particle size (A) Detection of 1.0 ppm NO in air at 250°C by sol-gel synthesized In203 response denotes relative resistance changes, S=Rjas/Rair, wheiB Rgas and Rair denote the sensor resistance in the presence and in the absence of the NO [6] (B) Detection of 500 ppm CO flame-spray-synthesized (FSP) SnO [7]. With increasing particle diameter the resistance in air, in 500 ppm CO and in 1000 ppm CO decreases. Also the sensor signal for 500 ppm CO decreases with increasing particle size. The measurements have been performed on drop-coated sensors at 350°C (8/3-FSP and commercial powders) and screen-printed sensors at 400°C (5/5-FSP powder) in dry air.

However, in the development of chemical and biosensors, new pastes must usually be developed. Polymer thick films can be screen printed on cheap polymer substrates with a thickness anywhere between 5 and 50 /xm. Importantly, no high-temperature steps are involved in the deposition process. The first commercial planar electrochemical glucose sensor (the ExacTech by MediSense) was a screen-printed sensor. A comparison of thick-film deposition against thin-film deposition is shown in table 3.10. 

Although ferrocenes have shown themselves to be excellent mediators of enzyme electron transfer in solution, they need to be incorporated into a fabrication process to produce sensors that are suitable for clinical use. The demands of implanted sensors are quite different from those that typically use a fingerstick for ex vivo measurement." The former is described later in this review this section covers screen printed sensors. The process of screen printing lends itself well to the manufacture of disposable, single-use sensorsand has been widely employed for this in both the laboratory and in large-scale manufacture. 

The method used to measure the activity of immobilized biological materials can interfere with the operational activity. PSII complexes isolated Irom the thermophilic cyanobacterium Synechococcus elongatus and immobilized in BSA-glutaraldehyde on the surface of a screen-printed sensor composed of a graphite working electrode and Ag/AgCl reference electrode shown a weak operational half-life of about 8h if the electrodes were coupled and a good half-life (24h) with separated electrodes. The low stability with the coupled electrodes was caused by Ag ions released from the reference electrode, which were toxic for PSII activity. In the same way, the operational life of whole... 

FIGURE 5.6 The portable sensor system for metal ions analysis. Screen-printed sensor (fabricated at Cranfield University) conpled to a portable electrochemical instrnment (PalmSense, Palm Instruments BV). 

In this section, a genosensor for the simultaneous detection of two of the principal causative bacteria of community acquired pneumonia is developed using a dual screen-printed sensor. The genosensor design is the same that the used in the previous section (see Fig. 9.14). 

Glass-silicon sandwich structure solder bumped Reduced light loss ShellOP (Shellcase) CCD cameras, digital photography, finger-print sensors... 

Shepherd, R.L., J.N. Barisci, W.A. ColHer, A.L. Hart, A.C. Partridge, and G.G. Wallace. 2002. Development of conducting polymer coated screen-printed sensors for measurement of volatile compounds. Electroanalysis 14 575-582. 

Mattana et al. (2013) reported using stainless steel yams for this purpose. The yams were aligned with the strips and conductive epoxy was applied to bind them together. The observations showed a very linear behaviour of the sensors, which was needed in order to apply Eq. [23.2] and calculate the resulting temperature. However, it was noted that the printed sensors had a temperature coefficient of resistance quite a bit lower than the sensors made with more conventional techniques such as photolithography. 

Manufacturing methods are aiming to obtain a film, usually composed of multilayers. Some materials such as Kapton are often sold in a film form. However, for resistive sensors, the polymers need to be applied by using dip coating or spin coating techniques. Weremczuk et al. (2012) have reported the use of an inkjet printer to draw a specific pattern for the electrodes over a layer of Nafion . The printed sensor demonstrated satisfying results but the durability and long-term stability are still an issue. 

---