Table 3.

Recent progress in PA and MIR combined spectroscopy for glucose detection.

Date	Reference	Source	Wavenumber (cm${}^{-1}$)	Samples	G. conc. (mg/dL)	Correlation or Sensitivity	M.L.	Main Contributions
2005	Toal et al. [20]	QCL	P:1080 Bg:1066	Forearm	0–300	R = 0.61	No	The PA and MIR combination
2012	Kottmann et al. [21]	QCL	P:1034	Epidermal samples	0–2000	$\pm 100$ mg/dL	No	Using tunable QCLs and N${}_2$ ventilation
2012	Pleitez et al. [25]	EC-QCL	P:1054&1084 Bg:1100	Palm	80–260	R = 0.70	R.O.	Selecting three wavelengths
2013	Kottmann et al. [24]	EC-QCL	P:1034	Glucose solution	0–5000	$\pm 57$ mg/dL	No	Fiber optics for light delivering
2013	Pleitez et al. [27]	EC-QCL	1000–1220	Hypothenar	40–240	-	R.O.	Removing noise by multivariate models
2016	Kottmann et al. [26]	EC-QCL	P:1080 Bg:1180	Fingertip & forearm	90–170	$\pm 30$ mg/dL	R.O.	Stability improved by increasing pulse rate
2017	Sim et al. [28]	EC-QCL	950–1245	Fingertip & palm	100–250	30%	R.O.	Studying skin effect on measurement

G. conc.: glucose concentration, P: peak, Bg: background, R.O.: regression only.